Mineral Resources Potential - Geothermal Resources

Mineral Resources Potential 

of Ethiopia 

Solomon Tadesse

;; 

5 

Mineral Resources Potential 

i of Ethiopia 

Solomon Tadesse

I@&h9969, 

I, zs3auozgR 

m,:m 

tn-ll;niMi 

.'ida~.qt@~qPp~ 

a C.. . fI 

Mdis Ethiopia 

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.... 

Chapter two 

'. . - 

Geological outline .,. . .......... "..H .... ...*..*...I....H 5 

2.1 Geology ....................... . ............................ 5 

2.1.1 Precambrian metamorphic 

rocks and associated 

intrusions ...............................I............. 5 

2.1.2 Late-Palaeozoic and Early- 

Mesozoic sediments ............................. 6 

2.1.3 Cenozoic rocks ................................. .-.. 9 

2.1.3.1 Cenozoic sedimentary 

rocks ....................................... 9 

2.1.3.2 Cenozoic vol~c rocks ......... 9 

r 2. I .3.3 The Rift and RiR 

volcanic rocks ................... . 10 

2.2 An overview of the main 

structural features in Ethiopia ........................... 17 

2.3 Mineral resources .............................................. 22 

Chapter three 

I 

Metallic minerals ............. -.*,. . . .... "..-... 32 

3.1 Gold Deposit ........... ....... .....I. ..++........ ............. 34 

3.2 Platinum Deposit ............................................. 71 

( 

3.3 Tantalum (Niobium, FEE, Lithium, 

I Beryliium) deposit ......................................... .78 

3,4 Nickel (Cobalt) deposit .................................... 95 

3.5 Irondeposit I .................................................... 100

3.6 Chromite ....................................................... 109 

3.7 Manganese deposit .......................................... f 11 

. 8 ~ a s d metals (Copper. Zinc. Lead, 

................... .***... 

Molybdenum. Wolfram) deposit .+ 113 

Radioactive minerals (Uranium. Thorium) 

posit ......................................................... 120 

ntite 122 

......................................................... 

.,. ... 

{* *" ..'.'"'.."*'*.. 'H w n ' r T41PJ. i .... 

.. I 

.... Industrial minerals . .....m..w.......~mm.*.mm.....*..m....1* f 23 

4.1 Soda ash (sodium carbonate) .......................... 125 

4.2 Diatomite ........................................................ 127 

4.3 Bentonite ....................................................... 129 

4.4 Other clays and kaolin .................................... 130 

4.5 Common-sdt ................................................ I33 

4.6 Magnesite ....................*.... . ............ 135 

4.7 Feldspars (Ceramic and sheet glass raw 

materials) ......... . .............. ....... 137 

4.8 Talc ........................... . ................................ 139 

4.9 Kyanite .................................,..................... i. ... 140 

4.10 Graphite ........................................................... 141 

4.11 Silica ................... . .......................... 142 

4.12 Quartz ........................................................ 1 4 4 

4.13 Mica ................... . .................................... 145 

4.14 Agrominerals ................................................... 146 

4.15 Phosphate ................... . ............................. N 

4.16 Gypsum. anhydrite ........................................ 150 

4.17 Potash ............................................................. 152 

4.1 8 Dolomite and Limestone ................................. 154 

4.19 Sulphurs ...................................................... 158 

4 -20 Pumicelscoria .................................................. 160 

4.21 Natd zeolite ................................................. 161 

4.22 Mineral waters ................................................ 163

423 Other metallic and industrid Minerals ........... 164 

Chapter five 

Constraction material and dimension stones 166 

Chapter six 

.............. 

5.1 Marble ..................................... . ........................ 167 

5.2 Limedone ....................................................... 170 

5.3 Granite ............................................................. 173 

5.4 Sandstone ....................................................... 178 

5.5 Volcanic rocks ................................................ 181 

5.6 Cement raw material ....................................... 181 

Gemstones and semi-precious stones ........ . ............. 183 

....................... 

................................................... 

... 

.....................*....... . 

6.5 Garnet .............................................................. 

6.6 Qudz ............... i .............................................. 

... .- .. ? . 

6.1 Corundum (ruby and sapphire) 189 

6.2 Opal .... ....... 190 

192 

6.3 Beryl ............................................................. 

6.4 Olivine (peridot) . 192 

6.7 Diamond .............,. ...>I.. 

.r......... , ..... WYtW'r'ir****- 

... 

Chapter seven 

Energy resources." .................. .....- ...... , 

193 

195 

195 

.......... 199 

7.1 Fossil fuel ....................................................... 199 

7.1.1 cod ...................................... 209 

7.1.2 Oilandgas ........................... 215 

7.1.3 Oil shale ............................... 221 

7.2 Geothermal resources ..................... . ............ 222 

....................................... 

7.3 Hydroelectric pqwer' 232 

Snmmary and conclmions .............. .+ ...".. " .......... 

., .,., ........ 237

. . 

,, i,!'!' ,,,, : I , :: , . , ,, 

I ' 

;!' . ., 4 1 

mm.1 ,: ,,!,.f~ ;I, i;:, -,I:.) t:. ; , ' , .:, . . 

Maj:og..mind. deposits of Ethiopia ('A; 'Ij 

: 

, ,;I -3:: - 2 ' 

I 8 , - 

8t C ,class) ......................................................... i *. ..256 

, . 

I 

pifi'n&x-2A 

M*r mhtral deposits of Ethiopia: 

CC1a~s D, E,N/A) ...........................I..r I.!I1.II.i ........I..... 262 

.Annex 3 . . 

. a . , 

'Defmitiofis of geologicalltechnical terps , ., * , I . j a 

. - dinthebook ......................................................... 281 

, , 

, &,eq 4 ( 

., . . L 

Techniqws utilized in digit'izing the 

geology and mineral map of Ethiopia ............. .L.. ... 285 

Apnex 5 

Mining law and-investment oppartmities: 

in Ethiopia .......................................... l... .;... ........ 289

t 

I 

Preface 

This baok is not the first of its kind. A similar work exists in the 

archives of the Ministry of Mines and Energy entitled Mineral 

, Occurrences of Ethiopia (Jelenc, 1966). This work, compiled over 

t 

forty years ago, does not indude some-of the new developments in 

the field. Other works on industrial minds and rocks were 

compiled by Magistu and Fentaw (2000). There are also other 

unpublished reports, mainly by the Ministry of Mines and Energy 

and the Ethiopian Mineral Resources Development Corporation 

(EMRDC), which are technical reports on specific mind 

resources of the country, 

The author has, therefor&, been encouraged to the 

present work to fill the existing gap and the strong need of scholars 

and the general public for a comprehensive and up-to-date 

reference material. The primary aim and important feature of this 

book are the possibilities it provided for a systematic digital 

compilation of various studies of the mineral and energy RSO& 

of the country in a single volume. The aim of this book is, first and 

foremost to provide readers an insight into the principal mineral 

' and energy resouroes of the country and to describe these mineral 

morns in relation to their geological environments by which an 

insight into their present usefulness and the mineral outlook of the 

I various parts of the country in the future can be obtained. The 

published data are complemented by unpublished information 

r 

provided by various authors, wjld further updated through 

compilation of geological, economic and metallogenic elements 

gleaned from recent literature. 

This work also presents geo-scientific maps and databases 

i for geology and mineral and energy resources of the country in a 

digital form at a synthetic scale of 1:2,000,000. The mineral 

occurrence maps display a compilation of the spatial distributions' 

' 

of over 650 data entries. Based on earlier works dating from those 

of Jelenc (1966) up to the recent syntheses by, but not limited to, the

ii Mineral Resources Potential of Ethiopia 

following authors: Senbeto and de Wit (1981); EMRDC (1985); 

Ethiopian Geological Survey (EGS, 1989); Getaneh and Saxena 

(1984); Getaneh Assefa (1985, 1991); Wolela et al. (1986, 1987); 1 

Wolela (1991, 1992, 1995); Gebre (1991); Meseret Teklemariarn 

(1 991, 1993,2000); Befekadu and Senbeto (1993); Abera (1 994); 

Ethiopian Ministry of Mines and Energy (1995); Tefera et al. 

(1996); Walle (1 996); Solomon Tadesse and Zerihun Desta (1 996); 

Solomon et al. (1997); Solomon Tadesse (1999; 2000; 2001); 

Meseret et aI. (2000); Selassie and Reymold (2000); Mengistu and 

Fentaw (2000); and Solomon Tadesse et al. (1998, 2003); along 

with the author's own long and direct experiences and scholarly 

research in many localities of Ethiopia. 

The author believes that the book is reasonably 

comprehensive and systematic in its treatment of topics and hopes 

that it will be of interest to both scholars and the general public. 

The book is intended as a text of reference for both undergraduate 

and graduate students in the field of Economic Geology, Mining 

Geology and Exploration Geology in the Department of Earth 

Sciences of the Addis Ababa University and other universities in 

Ethiopia offering related courses. It is hoped that it will be a useful 

guide and encourage potential local and foreign investors in 

undertaking mineral exploration activities and perhaps be useful 

also in identifying locations likely to produce new occurrences of 

minerals in the country. 

Chapter one begins with an introduction presenting a 

historical review of the country's mining and mind exploration 

and development activities. Chapter two comprehensive1 y reviews 

the regional geological and tectonic framework ofqhe country with 

a summary of a broad stratigraphic unit. The chipter emphasizes 

the range of geological processes responsible for the formation of 

the enormously diverse resource types found in the country. 

Chapter three presents a systematic description of important 

metallic mineral resources. Pertinent information on origin, 

I 

I 

i 

I

Preface iii 

composition, application and production of the commodities are 

discussed. The chapter displays geo-scientific maps and a 

summw of all known mineral occurrences (location, deposit 

types, reserves, etc.) containing key geological parameters. 

Chapter four reviews industrial minerals and rocks of the country 

describing them in a same patterti as the rnetdlic mineral 

resources. Chapter five reviews construction and building mate~ials 

in relation to their geological environment. Chapter six discusses 

gemstone resources with their geological context. Geological 

sources of energy such as natural fossil fuels (coal, oil and gas) and 

geothermal energy are considered in chapter seven. 

Geologically, Ethiopia lies at the northern end of the 

contjnental part of the East Afican Rift. Voluminous piles of 

mainly Tertiary volcanic rocks occupy large parts of the country 

along the Rift Valley. Proterozoic rocks occur in northern Tigray, 

western Wollega, southern Adola, south-western Akobo, and the 

eastern Harar part of the country; and Mesozoic rocks occur in 

north Mekele Outlier, central Abay Basin and Mugher, south-east 

Ogaden. Tewtiary rocks underlie most of the eastern and western 

part of the country. The floor of the Rift Valley is filled with 

relatively young lacustrine sediments and volcanics. Several 

alkaline plugs are known from Ethiopia, but no carbonatite has 

been identified as yet. Metallic resources (precious, rare, base and 

ferrous-fernalloy metals) are generally related to the 'metamorphic 

metavolcano-sedimentary belts and associated intrusives belonging 

to'various terraines of the Arabo-Nubian Shield welded together 

during the East and West Gondwana collisional orogeny 

(Neoproterozoic, 900-5 00 Ma) -a potential greenstone belt. 

Industrial mineral and rocks occur in more diverse geological 

' environments including the Qoterozoic basement rocks, the Late 

Paleozoic to Mesozoic sediments and Recent (Cainomic) volcanic 

amnd associated sediments. Energy resources (oil, coal, geothermal

iv Mineral Resources Potential of Ethimia 

mwces) are restricted to Phanerozoic basin sediments and 

Cainomic volcanism and rifting ctreas. 

In preparing this wbrk, I have, co~ously or 

.* unconsciously, been influenced by methods, statements, 

illustrations, a. that have appeared in other books or publications. 

So, I have tried to acknowledge my indebtedness, in general in 

scholarly terms, but, if I have failed to mention all, I wish to 

express aplogy and gratitude at the same time. 

I am particularly grateful to the Ministry of Mines and 

Energy, the Petroleum Operation Department, the Ethiopian 

Geological Survey, and the Ethiopian Mineral Development Share 

Co. for giving me access to their geological and mineral databases. 

A Mcular debt of gratitude is owed to Dr. Asfawossen Asrat, 

Dqmtment of Earth Sciences, Addis Ababa University, and a 

reviewer who undertook the onerous task of reviewing the entire 

manuscript. Their comments have helped me to b& to my 

, attention certain errors and omissions that were duly corrected. 

Finally, I thank the publisher, Addis Abaha University 

Press, for all the effort to produce the book in its present form. 

Solomon Tadesse (Ph.D.) Professor of Eoonomic Geology and 

Exploration Geology, Department of Earth Sciences, 

Addis Ababa University 

(E-mail: golotade@neol,w.edu.@ 

March 2008

Chapter One 

Introduction 

Mineral resources play a vital role in the eoonomic development of 

a country. The accelerating growth of the world's population 

cornbind with an improving standard of living throughout the 

world, greatly increases demand for mineral products of all types. 

The combination and development of the abilities of the 

explorations and of the scholars researchers of mineral sectors can 

effectively improve exploration and exploitation of the mineral 

resources. 

Ethiopia is endowed with a wide variety of minerals and 

rocks, some of which are available in large quantities and are of 

excellent quality. Minerals such as potash, bentonite, kyanite, 

diatomite, graphite, kaolin, marble, granite, limestone, gypum, 

sand, etc. occur in sufficiently large reserves that could warrant 

medium to large-scale mining. The history of mining in Ethiopia is 

comparatively recent. However, some mining activities such as 

iron mining and salt extraction were known in Ethiopia since time 

immemorial. Ethiopia has been a producer of gold, and such 

industrial minerals as brick-clay, diatomite, and feldspar, 

gemston-, granite, gypsum, dydrite, kaolin, limestone, pumice, 

salt, sand, scoria. The country also produced cements, lime, lignite, 

and steel. Ethiopia's main mined export is gold, limestone, 

marble, and gem, mainly opal. 

Mining for gold in the southern region of Ethiopia dates 

back to mid 1930's. Since then nearly 80 tons (EMRDC, 1985) of 

gold has been produced 6om placers of the Adola area alone and 

nearly 35 tons of gold from the Legadembi primary gold deposit 

(Midroc Legadembi) between 1991 and the end of 2007. No record 

is available on the gold production of the western and south- 

western regions. However, it is believed that local miners are 

producing a few kilograms of gold annually. Until' the

2 Mineral kurces Potential of Ethiopia 

establishment of mdern methods for the mining of the primary 

gold deposits of Legadembi and Sakaro, mining for gold was 

mainly carried out by primitive panning methods, employing 

significant number of labourers. The introduction of semi- 

mechanized mining methods, such as hydraulic 'monitors and 

dredging in the last 2 to 3 decades, has significantly inproved the 

production of gold in the Adola area 

Current mining activities include the production of tantalite 

and soda ash, on a pilot scale; primary gold from Legadembi; 

placer gold mining mainly from Adola; and mining of industrial 

minerals such as kaolin, dolomite, magnesite, and dimension 

stones (limestone, marble, granite, basalt, and sand) as well as 

sdl-scale artisanal mining of precious metals, gemstones and 

salt. Other undeveloped resources include copper, semiprecious 

gemstones (agate, aquamarine, chalcedony, chrysoprase, emerald, 

garnet, jasper, obsidian, ruby, sapphire, and spinel), manganese, 

molyt&num, mercury, nickel, palladium, platinum, rhdhn, 

tungsten, zinc, apatite, bentonite, dolomite, potash, and quartz. 

In the mineral industry these activities are dominated by the 

private sector. Some of the privately owned mining activities 

include the Dalleti Meteke1 marble which was purchased by the 

National Mining Corporation (NMC) from the previous Ethio- 

Libyan Joint Mining Company; Metekel marble by Tis Abay Plc; 

and Legadembi primary goId mine which was also purchased by 

Midroc Gold Mine (a subsidiary of Midroc Ethiopia Group). 

Mined prospecting and exploration in Ethiopia began 

around the end of the 18th century. However, modern minerals 

exploration started in 1968 with4fhe establishment of the EGS as a 

department within the Ministry of Mines and Energy to undertake 

surveys of the geology and potential mineral reserves of the 

country. Over the past 25 years, the EGS has carried out 

exploration for metallic, industrial and energy resources; the 

results of which are made available to investors.

I 

t 

Introduction 3 

A quarter of the total surface area of the country has teen 

1 geologicallymappedata~deof1:250,000,ofwhich20%has 

been geochemically surveyed at the same scale. Since the 

establishment of EGS and EMRDC, the Ethiopian government has 

undertaken various mined exploration projects. both 

independently and with the assistance of donor organizations. Until 

recently, systematic exploration for mine~als and mining activities 

have ken limited to parts of the country, principally to the Adola 

area (southern Ethiopia), where only a few resources have been 

found so far that would warrant large-scale mining. 

Surveys were carried out mostly in the Precambrian lowgrade 

metamorphic terrains. Exploration activities so far have 

outlined priority target areas and the reserve of the Adola placer 

gold, the Bombowha and Kombolcha kaolin, the Kenticha quartz, 

the Yubdo platinum, the Adola nickel, the Dallol potash, the 

Gewane Mille bentonite and the Lakes Region diatomite. Later, 

, modern investigation continued' and resulted in the discovery of 

important dewsits of gold, (such as Legadembi and Sakaro), the 

Keriticha columbotantalite, the Lakes Region soda ash (by 

EMRDC), the Bikilal iron and phosphate, the Yayu coal, the 

Bombowha and Komblcha kaolin, the Gewane bentonite, the 

Chembi kyite, the Dallol potash, the Afdera salt, the Kenticha 

magnesite, the Yita opal, the DaIeti and Metekel the Babile and 

Hamama granite, marble as well as other deposits. 

Although it is believed that there are different mineral 

occurrences in different part of the country, integrated explodon 

activities were not conducted at the appropriate scale required to 

1 assess all the potential areas for the economic deposits that would 

eventualIy foster the welI-being of the society. Some of the major 

I causes for mineral exploration problems in the country include: 

political instability, government policy in the mining sector, 

absence of geologicai maps at an appropriate scale, inaccessibility, 

unsuitable working conditions, non-integrated investigation and

41 Mhal Rmum Potential of Ethiopia 

.march works, and shortage of well-trained human resources. 

Burthermore, although many mineral deposits exist in Ethiopia, 

thick layers of voIcanic lava covers the older ore-bearing mlis, 

wbich renders exploration and exploitation difficult. Outcroppings 

-of iron, copper, zinc, and lead have been mined since ancient 

times, but deeper reserves of these minerals remain largely 

unexploited. 

The mineral industry, like other sectors such as agricdhue, 

contributes significantly to the economic development of the 

country. Therefore, effort should be made to explore the county's 

mineral aud energy resources by integrating studies and attracting 

local and foreign investors to the mind and energy sector.

Chapter 'Two 

Geological outline 

The main rock types recording the geological history of Ethiopia 

illustrated on the general and schematic framework of the geology 

of Ethiopia (Fig. I) are: 

- The Precambrian metamorphic rocks with associated syn-to 

post-tectonic intrusions which form the Basement 

Complex; 

- The Late-Palaeozoic to Mesozoic marine and continenla! 

sediments; 

- The Cenozoic 'basic and felsic volcanics and a 

volcano-sedimentary and volcanoclolstic rocks 

Early Telqiary, Late Tertiary and Quaternary volcanic. 

These rocks assemblages represent 23%, 25%, 34% and 

18% of the total surface area respectively. Such a diverse 

geological set up makes the country wealthy in mineral 

;, .--': 

resources of various types. The synthetic stratigraphic 

column including . . the miin units in p&sented in able 1 

! :- y $;

6 Mined Resources Potential of Ethimia 

country (Fig. 1 ). The basement in the south and west of the country 

where granitic rocks and gneisses predominate has been more 

strongly metamorphosed than the Precambrian sequences in the 

north. The highest metamorphic grade (granulite facies) has been 

recorded in gneisses of the southem and south-western prt of the 

country. Though in many cases strongly folded and foliated, the 

rocks in the north, which include the youngest formations (known 

in the basement), have generally undergone only very low to low 

grade metamorphism. The low-grade Upper Proterozoic rocks are 

exposed in the sou^ west, southwest and north forming the 

southern, western, the southwestern Akobo and the northern Tigray 

Gttenstone Regions, respectively. Most of the known metallic 

mineralizations hosted in these low grade metamorphic rocks are 

known over a tittle area in the east exhibiting lead and copper 

anomdies. A tbfold lithotectonic sequence has ken suggested 

for the Precambrian basement rocks of Ethiopia by Kamin (1 975) 

and Kazmin et al. (19781, consisting of a Lower, Middle and Upper 

Complex. However, recent geochronogical and isotopic studies 

suggest that this Precambrian basement (granite-gneiss, volcano- 

sedimentary and ophiolitic suite;) is dominantly Neopmterozoic in 

age (Aydew et d, 1990; Ghichile, 1992; Telclay et al., 1998; 

Gerra, 20001, and that the rocks previously attributed to the 

Archereoul or pre-Neopmteromic could be part of pre- 

Neoproterozoic continental crustal fragments e.g. Tulu Dimtu 

orogenic belt, western Ethiopia, (Tadesse G. ad Allen A., 2002), 

including possibly reworked and remobilizsd components, as 

indicated by Archaem zircon xenocrysts found by Teklay el a/. 

(1 998). 

2.13 Late-Pdaeozoic and EariyrMemmic Sediments 

The Paleozoic Era in Ethiopia is marked by a regional 

unconfonnity due to long period of penepwon. Late Paleozoic- 

Triusic sediments are widespread in Ethiopia as a result of the

. 

P : tmxgtew1~1a1~~isri. ofithe *a, and cover the Northern, 

r~ .W&aIi Eastem 'and Southeastem part of the eountry. The Late 

Palaeozoic to Triassic sedimentsx and tillitcis composed of 

sandstone, siltstone, shale, rmd.minor oonglommte (Table 1); have 

been mapped in several regions, These -sediments comprise the 

i Enticho Sandstones (thickness: 160 m; Timy), the Edaga .&bi 

I 

Glacial Sediments (thickness: 150-180 m; Tigr~y)+ $the Permian 

I Sandstone (south-western Ethiopia), the Gura 8andstone (SE 

! 

Ethiopia), the Middle Abay ~iilite (central E?hiopia)+h,tbe Waju, 

I ,Cdub, Gumburo Sandstones and the Bob Shttle (Qgaden, SW 

Ethispicd) and Gede Basin Glacial 'Tillites (Tadesse and Melaku, 

1 9981; 

The Mesozoic rocks were widely deposited in Ethiopia 

I during a continuous period of subsidence of the land and migration 

of the sea fmm the cast in the Ogaden wards the west and ~ n h . 

and covering the central part and northern areas of the country. 

. They rest unconformably on the Precambrian metamorphic rocks, 

filling channels in the basement rocks. Rocks of Mesozoic age are 

mainly sediments such as sandstone, limestone and gypsum. They 

cover the whole of the eastern lowlands of Ethiopia and large areas 

of Ham, Bale, Borenq and Tigray. They also outcrop in the upper 

valleys of the Blue Nile and its tributaries in central Ethiopia. 

The Mesozoic sedimenfb comprise: 

(i) The Lower or Adigrat Sandstone of Triassic age; 

(ii) Jurassic Limeston f Antalo group; and 

(iii) Cretaceous Upper andstone with mudstone and marl 

intercalations. T 

The Adigrat Sandstone' rests unconfomably on the 

basement. This sandstone, which varies from a few meters to 800 

m in thickness, is typically a yellowish to pink, fine to medium 

grained, non-calcareous, weil-sorted, cross-bedded quartz 

sandstone with interbedded siltstones and minor conglomerates. 

The Antalo Group incorporates the three formations which make 

9

up the marine Mmic sequence within the central Plateau. The 

type section of the Antalo Group, in the Abay Gorge in the Blue 

Nile Bash, totals 880 m (Getaneh, 1991). halo Limestone is 

typically developed in the Mekele area, where a 750 m thick 

sequence consists of fossiLifmus yellow iimestone and marl, 

In chmobgical order, the formations within this group are: 

- The Abay Beds (central Ethiopia, Middle Jurassic), which 

we mposed of limestones, calcareous sandstones, and 

shale and gypsum beds with a total thick of 580 m; 

- The Antalo Limestone (localized in different regions, Upper 

Jurassic, ("Oolithic Jurassic") consists of fossiliferous 

limestone, interbedded marl, calcareous shale and rare 

amaceow beds (thickness: up to 1400 m); 

- The Agula Shale (Tigray), Upper Jmic (Kimmeridgian) is 

connposed of shale, black shale, marl, claystone and minor 

limestone and dolomite (thickness: 60-250 m); 

- The Upper Sandstone (@retaceous) consists of sandstone, 

shale, marl, oolithic and dolomitic limestone and mim 

gypsum- andlor aatry drite-bearing beds deposited 

conformably on the Jurassic rocks in some mas, as in 

Western Ethiopia, and unconfonnably in others, ws in 

Tigmy region, 

The thickest and most complete succession of Mesozoic 

rocks are know in eastem and westem Ogaden and harghe 

region including upper Jurassic to Turonian Gabredam (Oolithic 

limestone, sandstone, marl, shale, and minor gypsum-bearing beds; 

thickness: 400-630 m), KO& (dolomitic limestone, marl, shale 

4 minor anhydrite-bearing beds; thickness: 100-500m), M&l 

(limestone, shale d marl), Ferfer (dolomite and clayish 

limestones; thickness: 100-200 m), Belet Uetl (limestone and 

glauconite shale; thickness: 90-230 m) and Amba Aradom 

(sandstone, shale, siltstone; thickness: 1 50-600 m) Formations 

2000). 

(a 

4,:

1, ' 

I; 

i wnthmtaI 

I '! 

. . 

Geological outline 9 

Tht Mesozoic formation comprising of sandstone, 

claystme, &sum, and limestone are important explomtion tafgets 

for fossil fuels such as oil and gas and coal; as well as sources of 

raw matorials for cement, glass and lime production; industrial 

mbrals such as clays, bentonite, diatomite and gpm; and 

metallic deposits such as oms of zinc, copper, lead, iron and 

manganese are deposited during this period and are to be looked 

forinthm mcks. 

2.l.3.l Cenomk dlmentary Pocks 

Sediments and volcano-sediments me intercalated ih various 

pmpor&iond with voldc episodes from the Early Tedq to the 

Qllirtemary. Cenozoic sedimentary rocks occur in eastern Ogadea, 

the Danakil depression, and the lower Ono Valley. Mark and 

sediments in eastern Ogaden, ranging from Palaeocene 

to Middle Eocene, have a tototal thickness of up to 1000 rn (Getaneh, 

1991), Late Tertiary to Quaternary sedimentary rocks assmiabed with 

volcanic rocks include clay, silt, sand, gravel, tuffs, marls and 

limestone of the Omo Group (1 5&750 m thick, 13-3 1) and clay, 

; siltstone, sandstone and conglomerates of the Hadar Formation (3& 

ZMnthieX.Z.M.I)Ma(Tslarnul.I996).S~~ofTdq 

.age, which are represented by smdstcmes, limestow, gypsum, 

dnhydrites etc., are known to *occur in eastern Ogaden, in the 

Danakill depression and in the Omo River valley. Quaternary 

sediments wre also widely distributed and genetically belong to 

lrtcwhhe and marine origin. 

Ir 

$ 

i - 

2.1.3.2 Cenozoic volcanic m b 

I : cmmzoic volcanic rocks (~athy 

to m t l m areassociated 

i . with the fonnation of the Main Ethiopian Rift, Afar depkmion and 

bae highland volcanic. The unit consists of halt, trolchytes and

10 Mineral Resources Potmtia! of Ethiopia - 

associated dyke swarms, andesites, rhyolite~, igninlbrites at:d 

pilrnice as ash. Highland Ethiopia is underlain mainly by Tertiary 

volcanic, mostly basalt. The Rifi Valley, which divides the Ell1 iopiarr 

highlands into the eastern and western Plateaus, is undel-lain by 

Tertiary as well as Quaternary volcanics and sediments. 'There are 

also alkaline and acidic intrusive which range in age from 

Mesozoic to Late Tertiary. 

Tertiary volcanic ("PI ateau volcanic"), the earliest and most 

extensive group of volcanic rocks is the "Trap Series". erupted 

from fissures during the Early Tertiary (54 Ma to I3 Ma, (Zanet~ir~ 

B, 1993; Tefera et al., 1996; Hofmann et al. 1997). The Trap Series 

consists of piles of flood basalts and ignimbrites. The basalts of ~i IC 

Trap Series are transitional from alkaline to tholeiitic in 

composition and erupted from fissures. The flows range in 

thickness from 500-1 500 rn (Mohr and Zanettin, 1988) to up to 30130 

m (Tefera et al., 1996). Shield volcanoes that consist mainly of 

porphyritic amygdaloidal olivine basalt overlie these rocks. 

2.1.3.3 The Rift and the Rift vohanic rocks 

The Great Rift Valley is a vast geographical and geological featurc 

that runs north to south for some 5,000 h from northern Syria ro 

central Mozambique in East Africa, The valley varies in nicl~h 

from 30- 100 km and in depth from a few hundred to sevem! 

thousand metres. It has been created through the rifting atid 

separation of the African and Arabian tectonic plates that began 

around 35 million years ago in the north, and by the ongoing 

separation of East Africa from the rest of Africa along the East 

African Rift, which began about 15 million years ago. 

The northernmost part of the Rift forms the Beqaa Valle> 

in Lebanon sepprating the Lebanon Mountains.To the south in 

Israel, it is khown as the Hula. Valley separating between the 

Galilee Mountains and the Golan Heights. Further south, the vuI Ic! 

becomes the Jordan River, which flows southward through t':*am

B 

? 

Geological outline 1 1 

Lake Hula into the Sea of ~dilee in Israel, and then continues 

south througb the: Jordan Valley into the Dead Sea on the Israeli- 

Jordanian border. $Am the Dead Sea southwards, the rift is 

occupied by the Wadi Arab& and then the Gulf of Aqaba and the 

Red Sea. 

The Western Rift, also called the Albertine Rift, is edged 

by some of the highest mbuntains in Africa, including the Virunga 

Mountains, Mitumba Mountains, and Ruwenzuri Range; and 

contains the Rift Valley Lakes, which incfude some of the deepest 

- lakes in the world (up to 1470 rneters deep at ]Lake Tanganyika). 

Lake Victoria, the second largest area freshwater lake in the world, 

[. is considered p~ of the Rift valley system, although it acidly lies 

It between the two' biiches, The other Great Lakes are dso formed 

,:. bytheRift. 

m8 In Kenya the valley is deepest to the north of Nairobi. As the 

Lakes in the Eas'tern Rift have no outlet to the sea, these lakes tend to 

be shallow and have s high mineral content as the evaporation of 

kter leaves the salts behind. The volcanic activity at this site and 

unusual concentration of hotspots has produced the volcanic 

mountains -Mount KUimanjaro,, Mount Kenya, Mount Karisimbi 

' 

Mount Nyimgongo, Mount Mcru and Mount Elgon as well as the 

Crater Highlands in Tanzania. The 01 Doinyci Lengai volcano 

remains active, and is currently the only natrocarbnatite volcano in 

j the world. 

7.. *.If. 

' 

,+ 

-1: l . - 4 - - 

.+ fit, :-I - 8 , - ,:>. 

. . I.

Map of East Africa showing some of the historically 

active volcanoes (the trianglss) and the Afar Triangle 

(shaded, center) -a triple junction where three plates 

are pulling away from one another: the Arabian Plate, 

and the ?wo PG3ftS ofthe African Plate (the Nubian and 

the Somalian) splitting along the East African Rifi 

Zone (USGS). 

The Ethiopian Rift is thi: northernmost extension of the 

great East Afrim Rift that extends from Nortb-Eastem Ethiopia to 

Mozambique in Southern Africa, with a length of more than 4,000 

krn. More than onequarter of the rift system lies in Ethiopia (Fig. 

1). The central Main Ethiopian Rift (MER) is a large 1 km deep 

graben with an average width of about 70-80 km and e length of 

700 krn stretching from the Ethiopian-Kenyan border in the south 

to the Afar Depression in the north (Dipaola, 1972). The riR 

dissects the highlands of the country into the eastern (Harar) and 

western (central Ethiopia) Plateaus and is bounded on two sides by


a series of large normal faults. The eastern escarpment of the MER 

is chamterized by steep faults with significant throws in its northeastern 

sector exceeding 1,500 m between the top of the Pldeau 

and the Rift floor. The westem margin is gradational and less 

marked thus accounting for the asymmetry of the MER, Active 

tectonic movements are confumed by numerous faults affecting 

Holocene rock units and by the intense recent seismicity of the 

I whole region. 

The Ethiopian Plateaus bordering the Rift consist of a-thick 

I succession of flood bdts and subordinate amounts of hyolites 

! emplaced during Eacene to middle Miocene (54 to 13-1 5 -my) 

: (Woldegabriel e6 al., 1990). The floor of the rift is commonly 

covered by Plio-Quaternary volcanic products and basin-fill 

i 

volcanmlastic sediments. Basaltic volcanic rocks (transitional 

from alldim to tholeiitic in composition) become progressively 

younger northwards to Afar, although young basaltic volcanism of 

. minor volume is also common along the axid zone of the 

! Ethiopian Rift. The main petrological feature of the MER is the 

abundance of felsic peralkaline volcanic (mainly pantellerites) 

related both to the fissd activity and to the several volcanoes 

rising from the rift floor. It has been suggested that east-west 

structures may be an important factor in controlling the locations 

of volcomisrn along the rift Thick sediment accumulations of 

hamsirhe origin cover large areas of the rift flmr. 

The Rift Valley has hen a rich sow of anthropological 

discovery, especially in the A h area. Because the rapidly eroding 

highlands have filled the valley with sediments, a favourable 

I environment for the preservation of remains has been created. The 

I bones of several hominid ancestors of modern humans have been 

found there, including those of "Lucy", a nearly complete 

dopithecine skeleton, which was discovered by 

anthm~logist Donald John. Richard and Meave Leakey have 

dm done significant work in this region.

~aln-ggrwpll ~lrln 

lll~ ~gpb) "complrx" Main 

mlckms8 types w 

MrW RIFT (cr m n W Om Maln Ethloplan Fwc 3TH . W) 

MWena ADEN) (1.3-nl~a) RUI 

S 

loaulim, - 

?5&7m) 

peralwne 

voleenlc 

WndU Fe,Mn) 

volePh 

n t s 

m n s 

LU 

0 ment5 

nlmr haab 311, Gas, 

volmnlm bal

Hamanlei Form.

g 

8 

2 

550-500 

Ma? 

Y7 

Pan African omgen 

Geological outline 1 7 

2.2 An overview of the main structuml features in Ethiopia 

The Precambrian 

WYEHT 

W-udmm 

sedimenta~y - 

ultlamfk 

belts 

(Neoproiemzolc 

'lhre wries) 

Gmnite- 

GwW 

TmW 

possi~. 

reworked - 

~emoblilred 

pm 

mqmmb 

(1 2 - 0.9 

Gal7 

Maln bxpo~urer hletamrphic rocks U 

ln BYkw 

N. pOst-l6dmk 

E ~ ~ I ttudvsa O ~ 

IrIgaY) 

, w, 

Emiopia 

' ponegal 

S. 

Ethkpla 

(Sibwno) 

E. 

Efiw. 

(Hams) 

Granuk 

fscle~ In S and 

Ethiopia 

lwgnde blrnodal 

ate- votcano 

a-lary island. 

The Pre-Cambrian basement structures constitute the oldest 

structures which also controlIed later stnrctural patterns. Two major 

Precmbri an (Neoproterozoic) tectono-stratigraphic units are 

recognized in Ethiopia: high-grade gneiss and low-grade meta- 

sediments (Fig. l ) . The gneissic *mck consists of polydeformed and 

metamorphosed schists and gneisses (biotite-hornblende gneiss and 

mphibolites). These rocks are comparable to the predominantly 

grreissic terraines of the Mozambique Belt described by Vail(1987, 

1988). The low-grade metamorphic volcano-sedimentary units 

consist of amphibolite, cmbonaceous quartz-mica schist, chlorite- 

arc 

W cph~olitZc sultes 

~ P W 

psammltlc - 

M~c met 

sediment& mema 

Wdle Cornplei') 

Hie- 

po(YmetamoQhased 

h h h a 

gnairgm. 

mlgrnatites 

("Lower Complefl 

Au,PGE, Ht 

1Co) 

Cu, Cr 

fe' Ti. (w W) 

Ta, (Nb, REE. 

s 

, .u. m) 

3k, Feld, 

ya. Qr Kln, 

& 

TIC,

18 Mineral Resources Potential or Ethiopia 

4 

actinolite schist, quartz-feldspar-biotite schist, meta-conglomerate 1 

and graphitic quartzite and mafic to ultramafic bodies. The q 

ultrabasic mks associated with the metavolcan~sedirnentan; I 

sequence form a N-S trending linear zone and occur as structurally 

modified and hdined lenses, extensively altered into serpentinite. 

talc-schist and talc-tremolite schist. These ophiolitic mafic- 

ultramafic belts could be interpreted, in accordance wih the models 

developed in the Arabian-Nubian Shield, as Neoproterozoic suture 

zones, along which different terranes were accreted during the 

Gondwana collision (Shackleton, 1994 and 1996; Stern, 1994; 

Abdeisalarn and Stern, 1997, Tadesse G. and Allen A., 2002). 

The greenstone sequence appeared correlatable to the 

volcano-sedimentary-ophiolite assemblage described for the most 

part of the Arabian-Nubian Shield by Vail (1987, 1988). Earlier 

a 

works (Kdn, 1972; EMRDC, 1985) suggested that the contact 

between the high grade gneiss and the low grade metamorphic 

volcano sedimentary unit is stratigraphical. However, detailed 

i 

1 

c 

I 

structural studies regarding the tectonic relationship between the 

volcano-sedimentaiand keiss rocks and the cont& between the 

4 

major lithologic units wi&n the greenstone belt by Beraki et d. 1 

1989; Hailu and Yifa, 1992; Gebreab, 1992 and Hailu, 1996 

Indicated that the contacts are of regional shear zone and me joined 14 

by ductile to brittle-ductile shear zone in a north-south direction. 

I 

These tectonic zones are characterized by strong development of 

schistosity and complexity in strucbwl features i d interking of 

different rock types evidenced by shear fabrics, mylonitic zones 

d textural variations. 

Most of the Precambrian volcano-sedimentary sequences 

sible greenstone belts) and associated intrusions have been 

ected to several orogenic episodes since their formation, in 1 

I 

I 

1 

8

Gmlogical uuliinr: 1 9 

Red Sea and the East African -Ethiopian Rift Valley, has resulted 

in considerable fracturing and shattering. Major water resowces 

are associated with these fracture zones. These ancient rocks and 

their minerals are exposed eithe~; because they were not covered by 

younger rocks as in northern and southwestern districts, or because 

younger rock cover was eroded away during subsequent uplifi and 

erosion. 

The ~alkmic and Memwic 

The Paleozoic Era in Ethiopia is marked by a regional 

unwnformity due to long period of peneplanation. Very few 

Paleozoic residual deposits (containing Precambrian basement 

debris and agglomerates) are observed on the peneplained surface 

in northern Ethiopia (e. g., Enticho Sandstone). 

Unlike the Paleozoic, the Mesozoic Era in Ethiopia is 

, marked by thick marine sedimentation and extensional tectonics, 

Several N W to SE striking structural basins have served as active 

depositional basins during the Mesozoic. Mesozoic sedimentation 

started with the Permo-Triassic to Jurassic deltaic .Adigrat 

Sandstone and was followed by a NE to SW marine transgressive 

sequence of Middle to Upper Jurassic Antalo Limestone, argillites 

and gypsum. It ended with the deposition of upward coarsening 

Cretaceous sandstone indicating regression, These Mesozoic 

transgressive and regressive sequences mark successive subsidence 

and uplift episodes of tectonism in the Horn of Africa between 

Permian and Cretaceous times (e.g., Boselini, 1989). Several 

extensional basins oriented N W to SE developed in Ethiopia during 

the Upper Jurassic to Fretaceous. The present Danakil-Red Sea 

region was already a strongly subsiding trough in early Jurassic 

time and this heralded the Tertiary breakup the Afro-Arabian plate, 

which gave rise to the present Red Sea.

, 

20 M i d Resources Potential of Ethiopia 

The Cenozoic 

The youngest structural features in Ethiopia are associated with the 

Main Ethiopian Rift System and Afar. The Main Ethiopian Rift 

(MER) constitutes the northemmost part of the East African Rifi 

System (EARS), connecting the Kenyan with the Afar triple 

junction. 

As it is well known, a rifting cycle begins with the 

activation of a hot spot below a craton; this convective movement 

of mantle material generates doming of the sialic crust,' fracturing 

of this dome along three directions (triple point), and rifting along 

these fractures, The three fractures are the M Sea, the Gulf of 

Aden, and the Ethio~jan Rift, which meet at the Afar Triangle. The 

Ethiopian Rift is lowland W extends from the Afar Triangle. 

through the Lakes District encompassing Lakes Zeway and . 

Chamo, to Me Turkana at the Kenyan barcierl East of the 

Ethiopian Rift (Eastern Highlands), major rivers like the Wabe 

Shebele, Weyb, Genale and Dawa flow eastward away from the 

if€ rim. West of the Ethiopian Rift valley (westem Highlands), 

major rivers like the Tekeze, Dinder, Abbay, and Baro flow 

westward away h m the rift rim. The river flow pattern, therefore, 

is amevidence of the doming of the region and its dissection by a 

riR valley. The three rift systems evolve at different speeds and 

degrees, and often at least one of them aborts (aulacogen). 

Thermal anomalies beneath the Arabian-Nubian Shield 

induced by a rising plume that mechanically and thmdly eroded 

the base of the mantle lithosphere and generated pulses of 

prodigious flood basalt since -30 Ma (Beyene and Abdelsalam, 

2005). Subsequent to the stretching and thinning the Mar Dome 

subsided to form the Afar Depression. The fragmentation of the 

Arabian-Nubim Shield led to the separation of the Nubian, 

Arabian and Somalian Plates along the Gulf of Aden, the Red Sea 

and the Main Ethiopian Rift. he southern end of the Red Sea 

marks a fork in the rift. The Afar Triangle or Danakil Depression 

. 3'

Geological outline 2.1 ' 

01' hhiopia and Eritrea is the probable location of a triple junction 

which is possibly underlain by a mantle plume. The Gulf of Aden 

is an eastward cai~tinuation of the Rift -before the rifi opened, the 

Arr~bian Peninsula was attached to the Horn of Africa and>from 

this point the rift continues as part of the Mid-oceanic ridge bf the 

Indian Ocean. In a southwest direction the fault continues as the 

Great Rift Valley, which split the older Ethiopian highlands into 

two halves: In eastern Africa the valley divides into two, the 

Eastern Rift and the Western Rift. . . . 

During Pliocene and Quatemar y, , the M ~ progressively R 

deepened, evolving through a sequence of interacting half-graben 

scgnzents marking the bun- between the Nubia and Somalia 

plutcs. The MER is limited by discontinimw boundary faults, 

adve from late Miocene ( WoldeGabriel et d, 1990) ad sdiking 

between NNE to SSW in the south and NE to SW in the n&.'The 

youngest part of the MER is the axial qne (Wonji,~au$&It, 

a 

( W FB)), mainly formed during the QuateGary (8oo;'etg: or. ol., 

1998). Despite the overall NE to SW uend of thi MBR; the'\3~8 is 

characterized by active NNE to SSW trending extension fmctwes 

and i~ormal faults. These &e often set in an emechelon 

arrangement and are associated with volcanic activity. If ,foll~~s' 

that the dome- rifi process is a possible explanation for tl$ great 

topographic relief in Ethiopia, which ranges from 0 in the Afar and 

the Red Sea coast to about 4,600 meters above sea level at rCas 

Das hen. 

Tk formation of the Rift Valley continues, *robably &ven ' 

by mantle plumes and ultimately a result of the African supaswell. 

The associated geothermal activity and spreading at the fie has 

caused the lithosphere to thin fmr~ a typical I@ km thickness for 

continents to a mere 20 km. Within a few~mi1lion yak, thi 

lithosphere may rupture and eastern Africa ~ HkpIit - off to hrm a 

nzw landmass. If spreading continues, this will 'head 'to ' the . 

formation of a new mid-qcean.ridge.

2.3 Mineral resouwes - 

The term "resource" refers to the amount commodity 

particular economic me that is present in an area These estimates 

include both extractable and non-extractable amounts of this 

commodity. 

Earth resohbs covered in this Book include: 

- Ore Deposits: which cin be further subdivided into (a) 

' 

@eci'ous metals (AU, Pt, Ag), (b) non-ferrous metals (as the 

' -base metals Pb, Zn, Cu, Sn, and elements like AI), (c) iron 

,,J,L and fmalloy metals (as Mn, Ni, Cr, Ti, Mo, W, V, and Co), 

(d) minor metals and related non-metals: Sb, As, Be, Bi. Cd, 

REE, Ta, Nb, Te, Ti, and Zr, (e) fissionable elements: U and 

Th; 

- Industrial minerds and rocks -graphite, sob ash, kaolin, 

diatomite, quartz, kyanite, gypsum, phosphate, sulfur, 

potash, asbestos, marble, granite, limestone, sand, basalt, 

etc; 

- Gemstones -diamond, ruby, sapphire, beryl, opal, zircon, 

garnets, etc; 

- Energy resources such as coal, oil, gas, geothermal energy. 

It should be pointed out that most if not all of the above 

mentioned resources are fairly common, and, indeed, do occur in 

many crustal rock types. However, their concentrations (or average 

crustal abundances) are so low that they are not easily extracted 

from these rocks. For an economic deposit to form, these 

"commodities" have to be conceptrated by some natural method. 

It is well known that different igneous rocks host ore 

deposits with deferent metal associations and that this must be 

reW somehow to the environments in which magmas are 

generated and the resulting composition-characteristics they inherit 

from 1 their various settings. It is widely recognized, for example, 

1

24 Mineral Resourca Potential of Ethiopia 

- Placer minerals sorted and distributed by flow of 

water (or ice); 

- Residual mineral deposits formed by weathering 

reactions at the earth's surface. 

Ore geumis processes 

Internal prmases 

These processes are integral physical phenomena and chemical 

reactions internal to magmas, generally in plutonic or volcanic 

rocks. These include: 

Fractional ctystallization, either creating monominerallic 

cumulate ores or contributing to the enrichment of ore 

minerals and metals; 

Liquation or liquid immiscibility, between melts of 

differing composition, usually sulfide segregations of 

nickel-copper-platinoid sulfides, oxides, carbonate and 

silicates. 

Hydrothermal proceses 

These processes are the physico-chemical phenomena and 

reactions caused by movement of hydrothermal waters within the 

crust often as a consequence of magmatic intrusion or tectonic 

upheavds. The foundations of hydrothermal processes are the 

source-transport-trap mechanism. Sources of hydrothermal 

solutions include seawater, formational brines (water trapped 

within sediments at deposition) and'metamorphic fluids created by 

dehydration of hydrous minerals during metamorphism. 

Metal sources may include a plethora of rocks. However, 

most metals of economic importance are carried as trace elements 

within rock-forming minerals, and so, may be liberated by 

hydrothermal processes. This happens because of:


- Incompatibility of the metal with its host mineral, for 

example zinc in calcite, which favours aqueous fluids in 

contact with the host mineral underkliagenesis, 

- Solubility of the host mineral within nascent 

hydrothermal solutions in the source rocks, for example 

mineral salts (halite), carbonates (cerussite), phosphates 

(monazite and thoriernite) and flllfates (kite); and 

- Elevated temperatures causing decomposition reactions 

of minerals. 

Transport by hydrothermal solutons usually requires a salt or other 

soluble species which can form a metal-bearing complex. These 

metal-bearing complexes hilitate transport of metals within 

aqueous solutions, generally as hydroxides, but also by processes 

similar to chelation. 

This process is especially well understood in gold 

metallogeny where various thiosulfate, chloride and other goldcarrying 

chemical complexes (notably tellurium~hloridelsulfate or 

antimony-chloridelsul fate). The majority of metal deposits formed 

by hydrothermal processes include sulfide minerals, indicating 

sulfur is om important metal-carrying complex. 

Sulfide depoaition 

Sulfide deposition within the trap zone occurs, when 4- 

carrying sulfate, sulfide or other complexes become chemically 

unstable due to one or more processes: falling ternpatme, which 

renders the complex unstable or metal insoluble loss of pressure, 

which has the same effect reaction with chemically reactive wall 

rocks, usually of reduced oxidation state, such as iron bearing 

rocks, mafic or ultramafic mks or carbonate rocks degassing of 

the hydrothermal fluid into a gas and water system, or boiling, 

which alters the metal carrying ,capacity of the solution and even 

destroys metal-carrying chemical complexes. Metal can dso 

nminitate when -&re and wessure or oxidation state favour

26 Mineral Resources Potential of Ethiopia 

Wmt ionic complexes in tlie water, f& instance the change 

froin sulfide to sulfate, oxygen fugacity, exchange of metals 

Ween sulfide and chloride mplexes, etc. 

Metamorphic p m e a 

Ore deposits formed by lateral d o n are formed by 

metamorphic reactions during shearing, which liberate mineral 

constituents such as quartz, sulfides, gold, carbodes and oxides 

from deforming rocks and focus these constituents into zones of 

redud p~~~ure or dilation such as faults. This may occur without 

much hydrothermal fluid flow, and this is typical of podiform 

chromite deposits. Metamorphic pmcewes a h control many 

physicd processes which form the source of hydrothermal fluids. 

Surficial procases are the physical and chemical phenomena 

which cause concentmion of ore material within the regolith, 

generally by the action of the &nvironment. This includes placer 

deposits, laterik deposits ad ~sidud or eluvial deposits. The 

physical processes of ore deposit formation in the surficial realm 

include: 

- Emsiondeposition by sedimentary pmwes, 

including winnowing, density separation (e.g. 

gold p ~ ~ ) ; 

- Weathering via oxidation or chemical attack of a 

rock either libemthg rock hgmmts or creating 

~hemically deposited clays, laterites or manto 

deposits.

Mineml msourowr of Ethiopia 

0001ogicaloutliw 27 

The -brim crystalline basement of Etbiopia is of particular 

interest due ta the fact that it hosts almost all known mined' 

commodities of the country (both metallic and industrial m inds 

and rocks), notably gold, platinum, rare-metals, nickel, copper, 

iron, chromium, kaolin, feldspar, clay, asbestos, talc, etc, Marble, 

limestone and granite are also common. Geological mapping and 

minerd exploration by EGS (1 989) show that among the crystdine 

basement terrain, the most promising areas for gold and base metal 

deposits are particulariy linked to the low-grade metamorphic 

volcano-sedimentary belts belonging to the 900-500 Ma Arabian- 

Nubian Shield terranes. 

The Mesozoic sediments are important for their associated 

industrial mheds and building material including Iimestones, 

sand, sandstones, gypsum and clays. Favomble conditions for oil 

and gas we also present. Early Tertiary formations show potential 

possibilities for lignite, opal, oil shale and lateritic iron ore. 

Bentonites, industrial clay minerals, perlite and pumice are 

common. Tertid anq Younger sediments host sulfur, diatomite, 

bentonite, potash, common salt, and perlite. Favourable conditions 

for oil and gas are also present. Rift volcanic and sediments are 

important for geothd energy, soda asb, epithermal gold, 

diatomite, bentonite, salt, sulfur, pumice, mineral water, etc. 

A flunmary of ore-deposit types (metallic and industrial 

minerals, wnstmction and building materiaIs) known to date in 

Ethiopia is presented in Table 2. Characteristics of main ore 

deposits (Class A: very large deposits; Class B: large deposits; 

Class c: medium deposits are summarized in Table 3 while small 

deposits (Class D), occurrenca (Class E) and deposits without 

available economic data (Class NIA) are presented in Annex 1. 

Locations of metallic mineral. deposits are presented in Figure 2 

and that of non-metallic mineral deposits in Figure 3.

28 Mineral Resources Potential of Mh'm~ia 

Table 2: Ore deposit types of Ethiopia

Asmas, lslc or mngncsite , 

-its hcsted by basic and 

UltrabaSIcrocks 

Volwic-hosted industrial rock G e m Mi, 

Cldlch Mad 

':guprgene ~ nsediment-~lated d 

inddd rock and mineral 

, deposits 

~Sedlmenr-related industrial 

Yrbo(Am@, 

Mekdh Mclh 

Jddu,&kkr 

y~xlks 

Valoanic-hosted industrial mk 

and mineral deposits 

Indu&i@l rock d minerals 

related to plutonic rocks, 

pegmatites 

hb tdon Wdet 

I 

I 

V o l c m idt&ial ~ 

Yila 

dmd mineral dqmh 

E v ~ ~ a tW e d SodDbk 

raksandmimrrls 

Industrid racks lad minerals 

datedto~icmcks; 

Mqdc 

S ~ . M a l m & d 

ilij&iAl deposi I 

InduslriPl mks and rnMk I CbcPM 

P 

Ulduslrial mks and mimls 

mhkd to plutonic rocks 

Slate, marbls and omammtal- DalcH, Morn, 

stonedewdts Bnruda 

LscuPRine Wits (sebkhs, Lnke Ablynl Lnk 

*, alkali& hkd , I ~hsla,LPkCCMlhl 

Sdb and gypsum depabits; 

lawtrine deposits (sebkha, 

dar, alkaline lake) 

Volcanic-hmtcd industrial mk 

and mineral deposlts 

- 

Gnluti, Hula - Kuni 

Wick Blik - 

Bmlba9a 

Axum, Adwa 

Hasereselm. 

Mhr, 

Adadikoto, Bissidimo 

valley Ramis valley 

-- 

Dire Dma, Cefenq 

Kelh, Jemma- 

Wdit, Shib 

Marecbi.Shebell-i

Geoloaicsll outline 3 1 

Sllc Sediment-related industrial 

iocka, and minerals; supergene 

deposits and minerals : Haghere 

Hiwot 

Dh-hmM~~k, Kechr,Mi 

IWbMmte. w 

Gimbicbo

I 

I 

Chapter Three 

Metallic Mineml Deposits 

Mttjor metaLIic. o~ , deposits of Etbiopirt include precious metals 

(Au, Pt), rare metals fTw) and Ni d Fe; some deposits are' 

currently mined for Au and Ta (e.g. Legadembi, Kenticha) or at an 

advanced stage of development (e,g. Bikilal project, Fe). To date, 

base metals (Zn, Pb, Cu) and &oy metals (Cr, Mo, Mn) are only 

knoknown as occurrences or non-economic sd-size deposits. 

Metallic resources are mostly genetically linked to the kctonothermal 

evolution of the various low-grade metamorphic volcaflosedimentary 

belts belonging. to the Upper Proterozoic (900-500 

- Ma) Arab-Nubian shield terrms -a potentid penstone hlt. 

' Aocording to the rqmtition of these belts, regional distribution of 

metallic mineral resources shows three distinct domains (Fig, 2 and 

E'ig. 4). 

1. A southern domain, including the meta-volcano-sedimentmy 

Adola and Kenticha belts (see Fig. 2b). The Adola Belt is one 

of the major Neoprobmzoic shear belts within the Pan- 

African bgen and this domain hosts major primary gold 

deposits (e.g. Lega Dembi mine, Megado, Sakcuo), the main 

Elthiopian gold placer deposits (Adola), the pegmatite-hosted 

Kenticha tantalum mine and the secondary Mte-dated 

nickel deppsits of the Adda district, 

Apemaryarn and h Greenstone Region: The 

Ageremaryam and the Arero Greenstone regions are located 

260 km and 100 km south-west of the town of Kibre Mengist 

and hosts: ma-Wc and meta-ultrabasic rocks related 

pyrite-bearing Au; meta-ultramafic rocks related Cr, Ni, Co, 

V; and Intermediate -to acid alkaline related rocks Bi Sn, W, 

Other isolated primary gold deposits in Southern Ethiopia 

under rsconnaissance are known in Moyale greenstone 

regions 200 krn southwar& close to the Moyale town and the

- Kenya border (e.g. Haramsam, Hasante). The Haramsam 

and IIaamte area is located 50 km east of the town of 

Moyde. The rocks in the area are, meta-grmodiorite, 

amphibolites, gabbro-amphibolite, gabro, and amphibolites 

schist. The Haramsam and Hasamte are considered potential 

mas for goid. 

2. A wide wmtem domain, following the Sudanese border; this 

domain can be subdivided into four belts, hosting primary 

gold deposits (e.g. Dul, Oda-Godere); the Yubdo platinum 

deposit md Meti-Tuludimtu platinum occurrences; the iron 

deposits of Bilikai, Chago, Gadma, and base metals 

prospects of volcanogenic-volcano sedimentary type 

(Abetselo, Kator), The predominant lithologies of the western 

Greenstone belt are chlorite, sericite and graphitic schists, 

phyuites, quartzites, and h itic to rhyolitic volcanic, iron- 

bearing quartzites and congIomerates are also present, The 

Akobo greenstone regions are potential areas for pIatinum, 

gold, copper and nickel. The area is underlained by mafic 

schist, meta-dtramafic rocks, metassdimentary schists and 

undifkrentiated schist and gneiss. 

3. A northern domain (Tigray) extending northwards in 

Eritrea, composed of several meta-volcano sedimentary belts 

and sub-belts, bounded by mafic-dEramelfic rocks, hosting 

gold and base-metal occurrences (e.g., Adi Zeresenay, Au; 

Werri, cu; and Mariam Adi Destra, lead-zinc). 

Significant metallic mineral sites located outside of these 

domains are scarce; they include the Melka Arba iron deposit 

(basic intrusion-related), the Chercher copper occurrence (Red Bed 

type in Mesozoic sandstones) and the Enkafala manganese deposit 

(Plio-Pleistocene sediments of the Dmakil depression). Therfore, 

potential investment areas in the m ind sector are concentrated in 

the Adola, Ageremaryarn, Arero, Moyale, western Akobo and 

Tigray greenstone regions and are considered as the best locations 

;&.

34 Mined Resources Potential or Ethiopia 

of metallic mineral deposits (gold, base metals, rare metals, Ni-Cr- 

Co and others), for potential investors to enjoy such rewarding 

business opportunities. 

3.1 Gold deposit 

Occurrence 

Due to its relative chemical inertness, gold is usually found as the 

native metal or alloy. Occasionally large accumulations of native 

gold (also known as nuggets) occur but usually gold occurs as 

minute grains. These grains occur between mineral grain 

boundaries or as inclusions within minerals. Common gold 

associations are quartz often as veins and sulfide minerals. The 

most common sulfide associations are pyrite, chalcopyrite, galena, 

sphalerite, arsenopyrite, stibnite and pyrrhotite. Rarer mineral 

associations are petzite, calaverite, sylvanite, muthrnannite, 

nagyagi te and krennerlte. 

Gold is widely distributed in the Earth's crust at a 

background level of 0.03 g11,000 kg (0.03 ppm by weight) (Boyle, 

1987). Hydrothermal ore deposits of gold occur in metamorphic 

rocks and igneous rocks -alluvial placer deposits originate from 

these sources. The primary source of gold is usually igneous rocks 

or surface concentrations. A deposit usually needs some form of 

secondary enrichment to form an economically viable ore deposit: 

either chemical or physical ,pro'cesses like erosion or solution or 

more generally metamorphism, which concentrates the gold in 

sulfide minerals or quartz. There are several primary deposit types; 

common ones are termed reef or vein. Primary deposits can be 

weathered and eroded, with most of the gold being transported into 

stream beds where it congregates with other heavy minerals to 

form placer deposits. In all these deposits the gold is in its native 

form. Another important ore type is in sedimentary black shale and 

limestone deposits containing finely disseminated gold and other 

platinum group metals. Gold occurs in sea water at 0.1 to 2 mg/t

I 987). 

Origin 

oed~g~&#&-$hg 

f ~ l 

W~QW 

flpih sm 1 @rectd..&mugh a structure 

~ ~ 

t*;&fmq$g=,%y~w7 @ 31~w c4dcal. wndi4i~ns 

@ , ~ ~ f f ~ t h4qmqWda p ~ ~ d ~ ae ~ minerals. @ i ane @ ~ 

@Y 

- - pr~du~e 

flm@:;mf 

~ m @gmo&&qy ~ c ~ s ~ p g s & g ~ ~ ~ t ~ 

$ r e 5 5 ~ ~ ~ ~ 

T@ -pmeqW~~of iqiaqsi~e rooks EUld altatipn associata 

, with.&qn .p.ro


Production 

Economic gold extraction can be achieved from ore grades as little 

as 0.5 g11,000 kg (0.5 ppm) on average in large easily mined 

deposits, typical ore grades in open-pit mines are 1-5 g/1,000 kg 

(1-5 ppm), ore grades in underground or hard rock mines are 

usually at least 3 g11,000 kg (3 ppm) on average. Ore grades of 30 

gl1,000 kg (30 opm) are usually needed before gold is visible to 

the naked eye. Therefore, in most gold mines you will not see any 

visible gold. 

Since the 1880% South Africa has been the source for a 

large proportion af the world's gold supply. Production in 1970 

accounted 'for 79?? of the world supply, producing about 1,000 

tonnes. However, production in 2004 was 342 tonnes (Boyle, 

1987). This decline was due to the increasing diaculty of 

exbction and changing economic factors affecting the industry in 

a that country. Other major producers are Canada, United States, 

Russia, and Australia Mines in South Dakota and Nevada sup&y 

two-thirds of gold used in the United States. Siberian regions of 

Russia also used to be significant in the global gold mining 

industry. Kolar Gold Fields in India is another example of a city 

being built on the greatest gold deposits in India. Today about one- 

quarter of the world gold output is estimated to originate from 

ions, southem Ethiopia.

Metallic M W s 37 

jewelry, gold is measured in karats (k), with pure gold being 24k. 

However, it is more commonly sold in lower measurements of 22k, 

18k, and 14k. A lower %" indicates a higher % of copper or silver 

mixed into the alloy, with silver being thc more corz~monly used 

metal between the two. Gold can be made into thread and used in 

embroidery. It pmkrrns critical functions in computers, 

communications equipment, spacecraft, jet aircraft engines, and a 

host of other products. It is also the form used as gold paint on 

ceramics prior to firing. Gold is used as a coating enabling 

biological material to be viewed under a scanning electron 

microscope (Jensen and Bateman, 1979), 

Gdd deposits in Ethiopia 

Primary goid deposit 

Primary and placer gold deposit and. occurrences have been 

reported from the Pan-African volcano-sedimentary sequence in 

Southern Ethiopia (Adola gold field), Western Ethiopia (Wollega 

region), South-Western Ethiopia (Akobo region), and Northern 

Ethiopia (Tigray region). However, at present the Adola gold field 

is the only existing active gold producing area except for small- 

scale placer gold mining activities by artisanal miners in the above 

mentioned regions. 

Primary gold sources were discovered in the 1980s during 

detailed exploration in the Adola gold field by EMRDC. Such work 

resulted in the discovery of the Legadembi and Sakaro primary 

gold deposits and many other primary gold occurrences. The 

Ethiopian investment company Midroc Gold (a subsidiary of 

Midroc Ethiopia Group) operated the Legakmbi gold mine in 

Southern Ethiopia; other gold mines that operated in Southern 

Ethiopia included the Adola and Sakaro field. Reported gold 

production fell to 3,443 kg in 2004 from 3.875 kg in 2003. In fiscal

! 

6 

i 

'14 

- 38 Mineral Resources Potential of Ethiopia 

year 2002-3, exports of gold amounted to about 5,000 kg at a value 

?' of $42 million, or 9% of total exports (international Monetary 

i - 

k 

'' Fund, 2005a). Midroc Gold planned to start underground 

operalions and to upgrade its processing plant at the Legadembi 

mine in 2008 that would increase gold production capacity from 

I 1 

2,800 kg per year to 4,700 kg. Midroc acquired the mine from the 

Government in March for $1 72 million. Midroc planned additional 

exploration and eventuaIly to expand the mine's capacity to 5,000 

kg per year, Midroc Gold Mine plc also acquired prospecting 

licenses for the Adoldkgadembi and Metekel projects, The 

company planned to explore for gold and rare-earth elements at the 

AdolalLegadembi prospect, which is north of the Legadembi Mine, 

and for gold at Metekel, in western Ethiopia. 

A global potential of more than 127 tons (Table 3) of 

primary gold can be estimated (,resources), based on present stage 

of knowledge, including the Adola gold field with Legadembi (62 

' 

tons Au; open-ended) (Midroc Gold Legadembi), Megado (23.76 

tons Au), Serdo (2.85 tons Au), Sakaro (30 tons Au), Wollena, 

Kmudu and the Western Ethiopia area with the Dul deposit (2.5 

tons Au) (EMRDC, 1985). 

There are various types of primary gold deposits (see Table 2): 

; (I) the orogenic mesothermal gold deposits being the dominant 

L type, (Il) some poorly known gold-bearing volcanogenic massive 

b 

I 

sulphides (VMSs) and secondary gossan-type occurrences and (I1 I) 

recently identified epithermal-type mineralization (Solomon 

Tadesse, 200 1 ). 

I The orogenic maotherma1 gold deposits 

Orogenic mesothermal lode deposits form dong, and are localizd 

to, major regional fault and fi.acture systems, but are actually 

located in secondary or tertiary structures. These vein deposits 

form hm hydrothema1 (hot aqueous) fluids, which were derived 

deep in the earth's crust at w medium geological temperature (250

Metallic Minerals 39 

to 40O0c). The fluids use the fault/fracture zones as permeable 

channels along which to tow from their region of origin untii they 

reach a point where in any of a number of factors -chemical 

reactions with country rock andlor changes. in the temperature 

andlor pressure -causes the fluids to precipitate. The gold 

precipitates out of solution along with the quartz vein material. 

These regional fault systems develop during the waning stages of 

continental collision and hence can form at significantly later 

periods than the host rocks; as such, they are termed "epigenetic." 

The actual host rocks of the orogenic mesotl~ern~al lode 

deposits are affected by these fnultlfracture origins and can range 

fmn mylonites to fault gouge. Mylonites indicate deformation 

under confining pressures sufficiently high that the rock 

recrystallizes to a fine grain size. This is plastic or ductile 

behavior, and indicates that the vein formed deep in the earth's 

am@, Alternatively, if the faultlfrachlre cuts a rock at a level cIose 

, to the earth's surface, then it does not have the same confining 

pressure and hence will break into fault gouge. 

Typical orogenic mesothermal lode gold deposits consist of 

quark veins with gold, pyrite andlor arsenopyrite, The gold is 

usually pure gold and can be present in textures ranging from 

solitary grains to grains intimately ii~tergrown with sulphide 

minerals. In some deposits, gold is present as "invisible" 

intergrowths with suIphj& minerals such as arsenopycite (that is, 

the gold is in the crystal lattice of the sulphide mineral). In other 

deposits, the gold is not pure but electnun -a mineral made up of 

gold, with 20% to 80% silver. Orogenic mesothermal vein gold 

systems are characterized by abundant, typically iron-rich, 

hydrothermal carbonate alteration assemblages which spread into 

the host rock from the vein. They represent pulses of fluid which 

flowed along the hctudfault plane into the surrounding country 

lock with which they am not in chemical equilibrium, producing 

chemical reactions and the resultant alteration halo.

4 MindResoums Potential of Ethiopia ;hcl 

: 

Alteration associated with gold mineralization also invdlvk?s :' 

;srflph.ildbtion (sulphide halos are a characteristic aitmtibs 

phgnbmenol~ of most orogenic mesothermal vein gold depasi@) 

.:ad potassium metasomatism (potassium is usually enriched in the 

alteration halo around the veins). These halos overprint preexisting 

alteration assemblages in the host rock. Any rock type can 

1. L - host these vein systems, but, at best, they are developed in d c 

'fo;cks such as badts, greenstones, gabbros and turbiditic shaky 

j. 

r 

I. 

i 

sedimentary rocks; this is attributable to the chemical contrasts 

between host rock and ore fluids. The ore fluids are silica-rich with 

Garbon dioxide and potassium; hence they react best with mafic 

rwcks, which-& not contain free silica but which have calciumiron-Magnesium 

silicates that can react with carbon dioxide to 

- form carbonate alteration minds. Gold abundance are characteristically Iow in most 

geological rnakrids, The average crustal abundance of gold is in 

, the order of three parts per billion, and generallyno single rock 

type is preferentially enriched in gold As a result of the low 

background contents of gold, a large mount of. rock must be 

affected by the hydrothernld fluids in brder for sufficient deposits 

of dissolved gold to be formed. The general model for these 

deposits suggests that the associated regional faults have deep 

roots that extend down to the lower crust, Hydrothermal fluids, 

which contain gold dissolved from a wide region, are formed, and 

these are focused up dong the M t s to higher levels in the crust, 

where they react with country rock to form lode gold ores. In 

temporal terms, orogenic rnesothd vein gold deposits 

apparently have ken restricted to specific intervals in the Earth's 

history, including the Late Archean, Early Pmterozoic. Early 

Paleozoic and Early Mesozoic periods. They are best deveIoped in 

Archean greenstone belts within Archean cratonic areas, such as in 

northern regions af Ontario and Quebec, Western Australia and 

Southern Afiica.

Omgenic mesolhermal gold deposits in Ethiopia 

Merallic M inds 41 

Most af the known primary orogenic mesothermal goId deposits 

and occurrences are related to shear-zone-hosted veins within the 

Neoprotmzoic volcan~sedimentary succession of greenschist to 

amphi bolite facies metamorphic rocks. They consist of 

a 

ampbibolite, carbonaceous quartz-feldspar-biotite schist, graphitic 

quartzite, me ta-sandstone and conglomerate and associated basicultrabasic 

intrusions, common in other greenstone belts of different 

ages, such as the Barberton (South Africa) and the Birimian 

volcano-sedimentary belts in West Africa (Milesi et d., 1992; 

Marcoux and Milesi, 1993; Ledru et a!., 1997), The auriferous 

quartz veins and lodes vary in length from a few meters to several 

hundred meters. The Kumudu ore occurrence is the smallest, about 

400 m in length, while the Legadembi deposit exceeds 3000 m in 

strike and 100 m in width. Individual quartz veins (e.g. Sakm) 

measure up to 580 m by 2 to 10 m, Most of the quartz veins and 

lodes strike confombly with the country rocks. Thus it is doubtful 

if they are really veins. Gold [fineness: 350-870 at Legadembi) 

occurs in veins as free particles (grains) or is contained within 

sulphides such as pyrite, gdena and chalcopyrite. Gold contents in 

the ore bodies reach up to 10 glt (e.g. Legdembi). The types oE 

wall rock alteration vary depending on the host rock types but are F!; 

" 

generally represented by sericitization, silicification, chloritization, 

sulphidization, carbonatization, serpentinkation and biotitization. 

Quartz and carbonates are the most common gangue minerals. 

Sulphides are generally associated with the gangues, but do not 

exceed 2% of the volume of the veins. The most common sulphides 

are galena, chalcopyrite, arsenopyrite, gyrrhotite and pyrite. 

Tellurides (petzite, altaite and hessite) are common, e.g. Legadembi 

(Solomon Tadesse 2000). 

With regard to the gold origin, most of the known primary 

gold deposits and occurrences in the region are concentrated within

-11 Minsral Rusourc~~ I'otzntial or Ethiopia 

the Megado Belt and partly in the Kenticha Belt which is filled by 

volcano-sedimentary (greenstone) rock associations (Upper 

Complex). The ore bodies known so far are located within these 

units or close to the shear contact with high-grade gneiss with the 

only exception of the Digati gold occurrence. Therefore, it is 

qbvious that this major structure (the Megado Belt) of the region 

served in the emplacement and deposition of the soutcelhost rocks 

and provided channel ways for the circulation of hydrothermal 

fluids during gold transportation and deposition. Thus, the model 

proposed belongs to the syn-orogenic mesathermal type with 

significant contributions for the source and trapping of the Pan- 

African deformation-metamorphism and magmatism events. The 

gold was most probably brought to the surface from a source of 

depth in association with basic-ultrabasic magmatism, during the 

opening of the Megado Belt (Solomon Tadesse, 2000). Later, due 

to metamorphism and defomtion, gold might have been leached 

from the protore and trapped at favourable structmI and 

lithological sites at various localities within the volcano- 

sedimentary sequence and at the contact of these rocks with the 

high-grade gneiss formations. Disseminated gold mineralintion 

associated with possibly sulphides-bearing veinlets is hosted by 

various meta-sediments such as quartzite's and mica-schists of the 

Adola Group and meta-conglomerates of the Kajimjti Beds. These 

deposits, often confined to Pan-African shear-zones and faults, 

probably also belong to the orogenic type mineralization. 

The Legadembi primary gold dewit 

The Legadembi primary gold deposit located in the Adola Belt, 

opia, is one of the major Neoproterozoic shear belts 

within the Pan-African Orogen. It is related to the shear zone- 

hosted vein system in the Neoproterozoic metamorphosed volcano- 

sedimentary succession of greenschist-to amphibolitefacies 

. The rocks consist of a sequence of biotite-feldspaf-

Metallic Mincrals 43 

quartz schists, carbonaceous mica-schists, amphibolites and basic 

to ultrabasic rocks. This unit is separated from footwall biotite 

gneiss by a major shear zone. The ore bodies are hosted in the 

volcano-sedimentary sequence and colisist of swarms of quartz 

veins, lenses, and stockworks that propagated along mesoscale 

dude to brittle-ductile shear;zones. The lithology of the facies 

occurring in the Legadembi deposit and surrounding area is briefly 

described below (Fig. 5). 

(i) Quartz-feldspar-mica-schist; gold mineralization at: the 

Legadembi mine occurs in quartz0 feldspathic mica-schist, and to 

some extent in actinolite-treinolite-hornblende schist. The schists 

are bounded to the east by non-mineralized biotite-quartzo- 

feldspathic gneiss and to the west by meta-gabbro. All these units 

dip at approximately 70" to the best and strike N-S direction. The 

quartzo-feldspathic mica-schist is about 1 00 rn thick. pinching out 

to the south. In the mine area, it occurs as discontinuous thrust- 

nappes units. It is composed of quartz, sericite, graphite, biotite, 

and plagioclase with disseminated sulphides. Biotite schist is 

dominant, but not the only host for gold mineralization; 

(ii) Biotite gneiss; this unit occurs to the east and adjacent to the 

eastern side of the Legadelnbi deposit, forming the footwall of the 

Legadembi-Sakaro thrust sequence. It is strongly foliated and 

contains porphyrodasts of quartz and feldspar. The only alteration 

seen in this biotite gneiss unit consists of minor quartz-sericite 

along the contact with the ultramafic rocks to the west; 

(iii) Ultramafic rocks; these rocks are strongly altered to chlorite- 

talc and tremolite-actinolite-talc rocks, with lesser chlorite schist, 

tremolite-actindite schist and graphitic quartz-mica-actinolite 

schist. They define the major shear zone that separates the upper 

greenschist facies meta-volcano-sedimentary sequence of the 

Megado Terrain from the upper arnphibolite facies gneisses. The 

altered meta-ultramafic rocks locally contain quartz veins that host 

gold mineraIization;

- , '''4; 

; ,q 

- 34 

44 Mineral Resources F~rential of Ethiopia ' < 4 

(iv) Metagabbdiamasiive to fol,iad coarse-grained metagabbm 

forms the hangfwvuall of the mineralized shear zone. It consists of 

basic plag i odd&'(i&adptite to, anorhit e), quartz, hornblende aud 

biotite. Nem tb~ontact 

of the miheralized zone, it displays fie- to 

medium-&&. tkkhms with plagiwlase laths (altered to a fine- 

- - 

grained &me of saicite, carbonate, chlorite and quartz) in a 

ma^^ of chlorite and minor calcite; 

(v) hphibolite; this fine-to medium-grained rock contains 

hodPde and plagioclase with magnetite por$hyroblasts. It 

exhibits a well-developed foliation conformable with the bedding 

df lhe regional rook Gentes; 

( ~ ) ~ ~ - gbeids:, ! I ? this ~ ~ rock ~ s is ~ medium to coarse grained, 

i6~&hgf~f6&ed, h'd mists of plrrgioclase, mono-smphibole and 

quark... It" .is. 2;lokel$ ' as-iated with amphibolik and is also 

elongated parallel to the 'reg$onal foliation ofthe Adola Belt. 

-

Ah Mincml RLWUKCS l'utential or Ethiopia 

mum 6 General panomma of he hga Dembi phuy gold deposit ' .

t 

,, . 

Ore minerals and mintrrml paragenesb 

metavolkano-sedimentary rocks in. the 

Microscopy and microprobe studies on Legadembi surface and 

underground samples indicate a complex mineral association 

consisting of gold-electrum accompanied by sulphides, tellurides, 

antimonides, and sulphosalts in variable abundances, with quartz, 

carbonate and silicates as gangue minerals. The following ore 

minerals were observed; pyrrotite, chalcopyrite, galena, pyrite, 

arsenopyrite, gold, electrum, altaite, hessite, petzite, cubanite, 

ullmanite, tetrahedtite, freibergite, breithauptite, boulangerite, 

bournonite, meneghinite, nisbite, gersdorffite and mackinawite. 

..- . 

. , 

, - .,. r . . . - 

, . ': . .. 

. . 

*' 1.. , '. 

., ..*$ ; 

8

'-& 

-. 

,.:& 

Metallic Minds 49. - 

- 

Based on different textural features of ore minerals and gangue.) rrs 

well as intergrowth relationships, the paragenetic sequence has 

been subdivided into four paragenetic stages. Stage one is 

characterized by an assemblages of pyrrhotite, chalcopyrite, 

sphalerite, cubanite, gersdofite, ulmanite, pentIandite and 

mackinswite. The sulphide minerals mainly occur in the wall rocks 

and me inherited as relic in awifmus quartz veins, In stage two, 

pyrite replaces pyrrhotite along grain boundaries. Finger-like 

protrusion of pyrite in pyrrhotite is common, Stage three is 

represented by the last pyrite generation. This pyrite stage occurs in 

late quartz veinlets cutting across the schistosity. Stage four 

includes gold, electrum, galena and tellurides. These minerals are 

confined to laminated or banded quark veins and their wall rocks, 

Gold and tellurides always occur as inclusions in galena pig. 9).

50 Mineral Resources Potential of Ethionia 

Possible genetic processes of the LDPGD 

1 Fofrnation of a volcano-sedimentary sequence, with mafic 

gold-bearing horizons interbedded at two main levels (within 

the lower most part of quartzo-feldspathic schist); 

2 RegionaI metamorphism of the entire sequence up to the 

amphibolite facies, with n~obilization and pre-concentration 

of ore minerals. Gold occurs as sub-micron to visible 

inclusions in and around the edges of galena and as free gold 

associated with tellurides, implying that the low temperature 

environment was a favorable condition for gold precipitation. 

The presence of gold as inclusions in galena, together with 

the absence of gold and galena in unmineralized wall rocks 

clearly supporls a temporal association of gold and galena; 

3 The intimate association between gold mineralization, 

metavolcano-sedimentary succession, brittle-ductile shear 

zones, lithological contrasts within the Neoproterozoic Pan- 

African Adola shear belt is, therefore, similar to most of the 

shear-zone-related and greenstone hosted gold deposits like 

those described by Robert and Brown, 1986 for Sigma mine, 

Canada and Aildrews et al, 1986 for Abitibi, Quebec.

. 46 

'& 


* 

Volcdc-associated massive sulphide (VMS) deposits qdi . 

throughout the-world and throughout the geological time col4 in:-"r 

nic domain that has submarine volcanic ~ cks 

uent. VMS deposits we major sources of Cu 

significant quantities of Au, Ag, Pb, Se, Cd, Bi, 

Sn qq We11 as minor amounts of other metals. As a group, VMS 

dap6% consist of massive accumulations of sulphide minerals 

(&o* than 60% sulphide minhs) which occur in lens-like or 

tai6ulm bodies parallel to the vofcanic stratigraphy or bedding. 

@ey are usually underlain by a footwall stockwork of vein and 

s&r sulphide mineralization and hydrothermal aheration. They 

my occur in any rock type, but the predominant hosts are volcanic 

rocks and fme-med, clay-rich sediments. The deposits consist of 

ubiquitous iron sulphide (pyrite, pyrrhotite) with chalmpyrite, 

sphalerite, and galena as the principal economic minerals. Barite 

and cherty silica are common gangue accessory minerals. 

As to the origin, at divergent boundaries, water from the 

ocean floor flows though fractures in the oceanic crust. The 

waters are heated by the nearby magma source, producing a 

seawater convection cell which reacts with neighboring rocks to 

leach out metals. These dissolved metals are transported to the 

ocean floor where they mix with cold bottom waters. The sudden 

decrease in temperature causes the minerals to precipitate from 

solution and they are incorporated into sediments deposited ahng 

the ocean ridge system. In Ethiopia, this type of mineralization 

warrants further investigations. 

III Epithermal gold deposit 

Epithermal precious metal mineralization is commonly associated 

with Cenozoic or Quaternary geothermal systems in areas of calc- 

alkaline volcanism. Much of this voIcanism typically occurs above 

subduction zones along continental margins and in Island Arcs as 

well as along spreading Mid-Ocean Ridges. Less commonly,

* 

western Asfa and continues along the eastern side of Mica. ThG ;, &' 

system already includes sectors that represent evolving 

basins (the Gulf of Aden and the Rsd Sea), but mostly it comptises 

sub-aerial intracratonic rifb, including the Ethiopian Rift Valley. 

Sub-aerial volcanism h the Ethiopian Rift Valley %has caused 

hydrothermal activity, which is still active in s v d sites being 

investigated for geothed energy. Extinct geothd fields are 

also quite common. The possibility that these gmthermd systems, 

related to the contined rifling, have been .and may be oreforming 

systems cannot be discarded a priori. 

An epithermal gold deposit is one in which the gold 

minerdidon occurs within 1 tp 2 km of surface and is deposited 

from hot fluids, The fluids are estimated to range in tempemhm 

from less than lOOC to hut 300C and, during the hdon of a 

&posit, can appear at the surface as hot springs, similar to those 

found in Yellowstone National Park (in northwestern Wyoming, 

muthem Montana and e&m Idaho). The deposits are mast often 

fomd in areas of active volcanism around the margins of 

continents. 

EpiEhermal gold mineralization can be formed from two 

types of chemical1 y distinct fluids -"low sulphidation' (LS) fluids, 

which are qduced and have a na-neu-tral pH (the measure of tb 

concentration of hydrogen ions) atld "high sdphidation" (HS) 

fluids, which are more oxidhd and acidic. LS fluids are a mixture 

of rainwater that has percolated into the subsurface and magmatic 

water (derived from a molten m k source deeper in the earth) that 

has risen toward the mfke. Gold is carried in ailution and; for LS 

waters, is deposited when the water approaches the surface and 

boils, HS fluids are mainly derived from a magmatic some a d 

deposit gold near the surface when the solution c ds or is diluted 

by mixing with rainwater. The gold in solution may come either


directly from the magma source or it may be leached out of the 

host volcanic rocks as the fluids travel through them. 

In both LS and HS models, fluids travel toward the s ace 

via fractures in the rock, and mineralization often occurs 4within 

these conduits. LS fluids usually form large cavity-filling veins, or 

a series of finer veins, called stockworks, that host the gold. The 

hotter, more acidic HS fluids penetrate Wer into the host rock, 

creating mineralization that may include veins but which is mostly 

scattered throughout the rock. LS deposits can also contain 

economic quantities of silver, and minor amounts of lead, zinc and 

copper, whereas HS systems often produce economic quantities of 

copper and some silver. Other minerals associated with LS systems 

are quartz (including chalcedony), carbonate, pyrite, sphalerite a h 

galena, whereas an HS system contains quartz, alunite, pyrite and 

copper sulphides such as erwgite. Geochemical exploration for 

these deposits can result in different chemical anomalies, 

depending on the type of mineralization involved, LS systems tend 

to be higher in zinc and lead, and lower in copper, with a high 

silver-to-gold ratio. HS systems can be higher in arsenic and 

copper with a lower silver-to-gold ratio. 

Epithermal gold occurrences in Ethiopia 

The Ethiopian Rift Valley in general held little more than an 

academic interest in scientific circles for a long period of time. 

Detailed geological studies and regional mapping of the rift valley 

have been conducted since the last 25 years. These have helped 

delineate specific industrial resources (e, g,, diatomite, bentonite, 

soda ash and geothermal steam), mainly through the work of the 

EGS. A new metallogenic province characterized by epithermal- 

type gold mineralization has been recently identified in Ethiopia 

(Solomon Tadesse, 200 1 ). Low sulphidation (adularia-sericite 

type) occ~cces have been found within Quaternary volcanoclastic 

rocks of the MER.

een dfted by intense hydro@errnal albratioq:. p90tassic and 

argillic alterations at Gedemsa $nd Tadaho, esqgntidly propylitic 

alteratio?.:a CorM. Thw, a lot of oaq and> ,cutting samples 

calbated. at various localities (such as Gedemsa, Aluto and 

Cbrbetti caldm, Tendaho . graben, Afar and MER) ,hve .revealed 

anoms ,wt~e~r~~ging hm ioo to 500 ppb (0.1-0.5 'gp~) gold. 

These sc?cuqremes warra4t fqrther investigzjtions. ,A new, field of 

inv%t&$gisn on epipithemal ore occmnces wldeb we ,und for 

th$ l ~ ~ ~ Ethiopian i a t metallogeflic scenery is .pmb&ly mergbfg. 

A,, study, ofl phe~~mena, in , lighl ,of @cent .rqc~ulsitions in 

~~a:how19dgeJ d d be, of potl ~Iytifor further 

u sci@c stugi but far new pgsib;ili~eq ini~&g activity. 

SQ&QO . aimed @ id~fiQjng epifiem&me, pmious metal 

$m&d$ gold), resources within the Ethiopian Rift is :relatively 

recent. , .. I , 

Geological setting and epithermal gold mineralization 

The Corbetti anidera 

Corbetti is a Holocene volcanic complex found in the central sector 

of the MER. The most abundant volcanic rocks are peralkaline 

py roclastics (ignirnbrite and pumice) which are attributed to 

central-type eruptions with subsequent volcano-tectonic collapse. 

The geometric outline of the resulting caldera is elliptical with its 

long axis measuring about 12 km. The wall of the caldera has a 

variable height between 50 and 200 m. Post-caldera activity is 

represented by the emplacement of two very recent volcanic 

4

k 

56 Mineral Rtsoum Potential of Ethiopia 

centers (Urji and Chabbi) situated on active faults that parallel the 

major structural zone of the rift systeni. The Urji and Chabbi 

centers have extended pumice flows and falls with minor obsidian 

flows. Both centers are at fumaroles stage. 

Several NNE trending minor no& faults cut all the 

volcanic rocks except the youngest products of the Urji and Chabbi 

centers. Eight shallow temp-grad boreholes have been sunk at 

different locations in and outside the caldera ranging in depth from 

50-200m. The boreholes were irregularly located but have enabled 

constructing shallow subsurface volcanic stratigraphy. 

Altered rock forms a roughly north-south elongated area 

some two kilometers Iong and several hundred meters wide. Steam 

activity is apparent only along the extremities of this zone, but it is 

possible that thick soil cover may have Masked the rest of the area. 

A low sulpkidation (adularia-sericite type) alteration processes are 

indicated by propylitic and advanced argillic assemblages in 

ignimbrite, pumice and rhyolite, The alteration is characterized by 

the presence of chlorite, kaolin, calcite and quartz. The metallic 

minerals found in the shallow &ill-chip samples include Fe- and 

Ti-oxides, sulphide minerals including pyrite and chalcopyrite and 

possibly Pb-bearing sulphosalts. The propylitic alteration, which is 

largely overprinted by later intermediate Wllic alteration, 

surrounds an elongated and discontinuous core of potassic 

alteration. Advanced argillic alteration is limited to areas in 

proximity to the vents. Crusts of salts and silica occur around the 

vents; some of these sdts are greenish in colour and appear to be 

ferrous iron and copper salts. Weakly developed surface alteration 

zones locally occur, with Fe and Ti oxides. Gold content, a1 though 

irregular or err&ic, commonly exceeds 150 ppb both in compact 

mks and in pumice fragments. The Corbetti caldera appears to be 

one of the most economically promising among the newly 

discovered occurrences.

p&ducts. 

The caldera itself is clearly a composite structure that 

requited from repeated collapses following large pliniad pyroclast~c 

' empioris?' The geometry of the caldera is almost circular, 

mear~whig tabout '1 0 km. The whole caldera structure is strongly 

d&&d~ by many large close1 y-spaced WE-SS W-trending fdts, 

6peddly at its earn pout. These faults belong to the Wonji Fault 

Belt @d manifest active tectonics within the rift Evidence for past 

hydrothermal activity is observed in the. north-west caldera ~ l l 

*&&'an a mall dome hide the caldera. Occurrema of several 

Wv&therind maniftistations are .also known along NNE hult lines 

iminediately outside the calderq proper. The fossil hydrothe& 

m&festations have oxidid pumiceous deposits with some 

&psition of silica. Two. shallow tempemure gradient wells have 

ken drilled within the Gedemsa caldera reaching depths of 1W 

and 200 m respectively, with rack cutting samples taken every 3m. 

Rhyolite Iavas, ignhbrite and pumice deposits represent 

rhe'host~rocks. The alteration belongs to the low-sulphidation type. 

The alteration forms a roughly NW elongated area some 5 km long

wide. Propylitic dtetatibln,~ which is 

tennedhk argillic alteration, surroun@ 

on. several &in quartz-duiaria ve~irrr 

hsic alaon. The occurrences are formed of 

,and granular quartz Carbonates and clay 

present. The ore-mineral assemblage includes 

, iron oxides, epidote, chtorite and 

caldera, pyrite occurs in fractured 

propylitized rhyolite, with m w mms of ptassic alteration and 

development of intermediaie argillic alteration. In the fractures, 

i thin veins of cavernous quartz with abundant copper sulphide 

dissemination, occur. Gold content ranges hm 100 to 440 ppb. 

This area appears to be the most promising among the lowsulphidation 

murrences. 

Auto volcano 

The Aluto volcanic complex is a Quaternevy volcanic center -: 

located dong the Wonji Fwult &It in the central seaor of the MER, 

' - 

The geology of this complex is relatively well-known from surface 

mapping supplemented by data on the deep stratigraphy and I 

struchue from eight deep exploratory wells that were sunk to ii 

depths ranging from 1,300 to 2,500 m 

$E!: . 

by EGS. 

L uj 

According .to Govatmi and Mewet Teklemariam (1993) .*. ! .. 

the oldest ~utcro~~in~ rocks in the area are found at the adjacent ; ,]eastern 

rift escarpment and consist mainly of siiicic volcanic~ . ,: :.L 

commonly known as the Tertiary ignimbrite unit. This unit is 

overlain by a fisfltral, basaltic unit known as Bofa Basalt, which in gk . I ,. .I :. 

turn is covered by sediments of lacustrine origin which also extend "-, 

over large areas-of the rift floor. Th volc&c products of duto 

volcanic centre itself consist of w succession qf ash-flow tuffs, 

silicic tuff breccia$, silicic domes and pumice flows. These 

volmic products are very young and are associated with surface 

thermal manifestations that consist of hot springs and fumaroles 

., I


with tempratures up to 95%- steaming grounds, silica sinter and 

travertine deposits. The hydrothermal deposit temperatures 

measured in the deq cxploratdry wells range from 88 b 335'C 

(Solomon Kebede, 1 986). 

The alteration observed in the studied samples froin Aluto 

includes an upper facies characterized by intermediate 'and 

propylitic assemblages. Intermediate argillic facies are typidy 

represented by smectite-group clay minerals; alteration intensity is 

variable, hm incipient groundmass argillification to almost 

pervasive metasomatism. The latter is best developed in rack units 

originally very rich in glass. Propylitic alteration includes the 

chmcteristic minerals, calcite, chlorite, quartz and epidote. The 

metallic minerals found in the studied samples mostly include 

oxides and sulphides. The oxides consist of magnetite, ilmenite, 

hematite and Ti-oxide. The sulphide minerals are pyrite, 

chalcopyrite, and sulphosalts possibly of Pb. Pyrite is the most 

abundant. Gold value ranges from few ppb to 100 ppb, 

The emd dab graben 

This graben is found further north in the Afar depression. It is a 

NW-SE trending graben about 50 lun wide and is the southern 

extension of the Afar active spreading zones where the active Erta 

Ale-Manda Harm volcanic ranges are situated. The A h axial 

: ranges are considered to be the exposed equivalents on land of the 

Red Sea oceanic spreading ridges (Barberi and Varet, 19771, 

The Tendaha graben exposes a thick succession of basalt 

flows of Pliocene age (known as the Afar Stratoid Series) at its 

borders. The graben is filled with thick lacustrine and alluvial 

1 deposits consisting of siltstone and sandstone. Very young basaltic 

flows and scoria cones (the Afar Axial Ranges) have be~n 

emplaced on top of the graben volcani-cIastic sediments. The axial. 

zone is also characterized by the ~resence of open fissms and

60 Mineral Rrsources Potential of Ethiopia 

,- 

numerous active faults which as a whole define the sites of active 

spreading. 

The fissures and faults are evidence of active and fossil 

hydrothermal deposits which extend for several kms along strike. 

In fact, the most interesting feature of this area is the extensive 

hydrothermal activity which is controlled by N W -SE trending 

normal faulting. h the Tmdaho rift, the hydrothermal activity in 

the area extends for several krns according to a general NW-SE 

trend and consists mainly of steaming grounds. Several veins 

preferably cut the rocks undergoing potassic altersttion. These 

veins, with variable strike mund NW-SE, range from veinlets a 

few meters long and a few cehheters thick to bodies several 

hundreds of meters long. The quartz forming in these veins may be 

chalcedony near the walls, but commonly the central part of the 

veins is drusy and colourless mmcrystalline quartz. The 

alteration is manifested by the presence of mined assemblages 

a including chlorite, smectite, vermiculite, epidote, adularia and 

1 . quartz. The sulphide minerals include pyrite, galena, chalcopyrite, 

stibnite and covelitt. Sarnples h m drill cores recovered for the 

purpose of exploratory geothermal energy have been analyzed for 

gold. Analysis of a few samples hrn a core in Tendaho (TDI) 

range in value fiom tens of pbb to 400 pbb Au. 

I 

PetPobgicrrl notes 

The volcanic rocks of the above described formations range in 

composition from alkali olivine basalts to peralkali rhyolite and 

have the following genevpl petrographic features. Ignimbrites: 

these rocks show a remarkable uniformity of composition over 

large areas. They are porphyritic pdkdine rhyolites with 

abundant glassy matrix usually constituted by a very fine glassy 

dust. The common phenacrysts are an orthoclase, acmite and 

faydite. Xenoliths of foreign rocks are abundant in the ignimbrites.


Peralkaline Rhyolite; these rocks are represented by some 

lava flows, lava domes and pumice flows. Petrographically, they 

appear to be always highly glassy, with variable contents of the 

following minerals: alkali feldspar, generally anorthoclase, acmite, 

alkali amphibole (riebeckite) and me fayalite and quartz. Basalts; 

in the studied area, the basalts are usually holocrystalline and show 

typical features of allcaline basalts. The mineralogic a1 assemblage 

is magnesia olivine, clinopyroxene of augite type, calc plagioclase, 

magnetite, ilmenite and rare small apatite crystals. 

'HE results obtained so far represent the first phase of 

studies on epithermal occurrences within the (MER) and Afar. 

Much work has to be done in order to arrive at a reasonably well- 

documented synthesis, However, a working hypothesis can be 

attempted as a basis for future detailed studies from the obtained 

observations and results. 

The different associations among ore-mined assemblages 

and alterations seem to reflect different levels of mineralization. 

This is shown at Corbetti and Gedemsa which are hosted in similar 

volcanic systems. At Corbetti the occurrence of base metals is 

accompanied essentially by propylitic alteration, while at 

Gedemsa, precious metals and quartz addaria occur, in association 

with potassic and argillic alterations. Gold is likely to originate 

from Precambrian basement, which is presumed to extend under 

the rift floor. Hydrothermal fluids rose through a network of 

Mum found within and outside the caldera, provided that a 

major hcture system was present that should serve as a plumbing 

system. In the Corbetti caldera, one possible source of the fluids 

may have been the two rhyolite domes near the road just north of 

the steaming ground structure which apparently represent an 

intedon between the NS structure (fault plane) and a contact 

between pyroclastic and a hard, impervious compact rock. This 

fluid channel way is marked by the abundant silica encrustation of 

the surfaces.

I' 

Other sidlar structures ~ b lof e driving solutions might 

exist that pdtentially ImaIize sites of gold enrichment. Irregular 

fracture system within the caldera cause sporadic aI teration and 

discrepant gold values in the same rock unit. The youngest pumice 

unit appears fresh (except where fractures offer reactive channels, 

e.g. steaming ground areas). Although the gold content is 

comparable to that of the underlying rocks, fiis may have resulted 

from the fluid supplied from almost neud solutions, because 

buffered by alkalis in underlying rocks, but still containing gold, 

permeated through the interface of rock-pumice and spread 

through the unconsolidated, highly permeable material. A further 

expansion, resulting in an adiabatic drop in pressure and 

temperature would enhance the precipitation of gold from the 

circulating solution. Mixing with surface water might also occur, 

that recharges the groundwater body which occurs dong the 

interface between the pumice-hard rocks. The high precipitation 

characterizing the area, the high permeability of the surface and the 

much lesser permeability of the underlying rocks all favored this 

model. The wide surface area offered by the pumice and its glassy 

nature, allow adsorption phenomena in the entire pumice unit. 

As far as the age of epithermal mineralization in the rift is 

concerned, no quantitative data are yet available. However, it has 

been established that in all areas, where gold occurrence has been 

documented, the host rocks are ignimbrites, rhyolite laws and 

pumice deposits, with subordinate basaltic rocks. Thus, the 

epithermal occurrences are mostly hosted in acidic rocks emitted 

from central volcanoes during Late Quaternary times, i.e. younger 

than 0.8 Ma in age. The overall characteristics of the known 

occurrences and the evolution of the central volcanoes within the 

rift and associated epithermal phenomena apparently define an 

individual, homogeneous metallogenic province within the rift. 

Analyses of a total of 579 core and cutting samples 

collected from 18 deep holes from the. studied locgities showed 

,. . :;;cy$&;- s ,& .+*t'? y .>;. .,,. Gj, L, .e.- ;=-

I Metallic Minerals 63 

gold contents that range from hundreds of ppb to 0.44 g/t. 

Concentrations ranging between 120-300 ppb are very common 

t 

throughout the geological profiles particularly at Corbetti and 

Gedemsa calderas and Tendaho graben. The mean gold content 

from the above 1ocaIities exceeds the maximum gold values 

1 

reported in literature i.e. 3 ppb for rhyolite and 5 ppb for the upper 

lithosphere. Nearly all the analyzed samples showed high 

anomalous values starting from a depth of four meters downwards. 

1 Obviously, it is too early to give any economic evaluation, but the 

field and analytical data appear encouraging for the development 

of exploration and a preliminary estimate for gold, at least in the 

t Corbetti, Gedemsa and Tendaho prospects. 

A$ simple calculation shows that the overall gold quantity is 

huge, For instance, taking an average value of I00 ppb for the gold 

I 

a 

dispersed in the upper uniformIy spread unwelded pumice unit 

having an average thickness of 40 m over a surface area of 50 km2, 

the total reserve (assuming a specific gravity of 0.9 for pumice) 

can be calculated to over 200 tons in just one of the caldera alone, 

i,e. a gold reserve level of an important mine. Obviously, at current 

mining exercise, 0.1 g/t average gold content is .too low for the 

wide pumice layer to be considered as economical. It is to be 

noted, however, that the bore holes used for the present evaluation 

were strategically located to intersect known fluid-driving 

s~ructures nor was it possible to have fdly representative 

composite core samples for assay. If systematic geophysical and 

exploration drilling directed for gold were done, the subsequent 

analysis might enable to identify high-grade gold concentration 

target areas even at shallow depth. 

IV Gold-bearing placer 

Plat gold deposits form as a result of the breakdown and 

-ring of existing gold concentrations, erosion of the

64 Mineral Resourax Potential of Ethiopia 

w-eathered material and, ultimately, the concenbration of that 

material at a variable distance from its source. The tam "placer" is 

derived from the Spanish word for sand bank or stream eddy. 

Placer deposits, in the strictest &me, are formed in river systems, 

but the tern is typically used to describe deposits formed in- glacial 

and beach environments. Placer gold deposits are formed when 

gold is carried from its source to its site of deposition and 

concentration by a surface erosional force such as rivers, glaciers, - 

oceans end (rare1 y) wind. 

The formation of gold placers is predicated by two 

fundamental physical properties of gold To begin with, gold is 

dense, with a specific gravity of 19.3 grrtms per cubic cm-among 

the highest for all known minerals or native elements. Also, gold is 

a native element rather than a mineral (the latter being a naturally 

, occurring inorganic chemical compound), and dws not readily 

react with other elements. A corollary of this second pint is that 

gold is difficult to dissolve out of rock or minerals. The original 

' source of the gold is unimportant, ranging, as it does, bm 

mesoaermal lode deposits to massive suiphide deposits to 

disseminated sulphides in bedrock to pre-existing placer systems. 

Placer deposits depend on an original pre-con&-tion of gold 

which can be liberated through weathering. Eluvial, or residual, 

placers are a type of placer deposit in which gold has undergone 

little transport and actually forrned on, or near, the original source 

through the weathering or erosion of host rock. Owing to its 

relative chemical inertness, gold remains behind while h 

Gold in placer systems is transported as discreet grains as a 

the metal's inertness. Such grains are said to be &td, as 

derived from the physical weathering and breakdown of


material (detritus) carried in the same erosional system, the gold 

grains must be transported by erosional agents operating with 

~~elatively higher energy than that needed to transport normal rock 

detritus. When the energy exerted by the erosional agent decreases, 

the gold and other dense detritus will stop moving. In the case of 

fluvial (or river) placer systems, detritai gold grains ad 

concentrated in those mas where the current of the stream slows, 

such as on the slow sides of beds in the river, on the downstream 

sides of islands or near sand bars. old grains move when energy 

is exerted on them by the -porting medium. The grains will 

continue to move until the medium loses sufficient energy, 

whereupon the gold grains will settle out of the transporting 

medium. 

An example of a fluvial placer gold deposit is a mature 

stream in a valley floor into which numerous subsidiary streams 

' 

flow. h glacial tills, gold is transported along with other detrital 

&rial until the glacier ceases to move, dropping the gold and 

detritus. The driving mechanism for the formation of placer 

deposits, therefore, is gravity. Another innate feature of placer gold 

deposits is that the material that hosts the gold is unconsolidated 

sediment (particulate rock that is not cemented together). The host 

sediment can range from gravels to sand in fluvial systems, as well 

as to various types of till in glacial deposits or beach sands. 

A "pay stre&" is the layer of sediment in a placer deposit 

which is enriched in particulate gold. In fluvial examples, the "pay .. 

streak" frequently occurs in sediments that lie directly on tap of :i!'l 

r: A 

bedrock. The "pay streak" will also contain other dense, hard or : 

inert minerals, such as magnetite, zircon, garnet or chromite, There 

is some debate as to whether nuggets in fluvial systems represent 

purely detrital fragments that were rounded in transport or are the 

nuclei upon which dissolved gold in the stream precipitated and 

grew. In some instances, gold &ns have greater finene 

. .

, suggesting either- .prefeferftiti~ 

most important in the Adda gold field. Dcluvial gold is known to 

!' occur on the hillsides of the Legadembi and S&m primary gold 

deposits and the Kumudu ore occurrence. In the Adola goldfield, 

placer deposits with contents averaging 0.1& or more of gold 

and with gold reserves of over 30 kg are classifid as "placer 

deposit", while those with lesser gold valws and reserves erre 

a termed 'bplacex occurrence". All gold placers are concentrated in 

the N-S hending Megado Belt. The economic gold con&ntratim 

of the placers occur in gravel, shd, silt and clay sediments of dry 

streams, river fl-, old vdIeys, and terraces. They are derived 

- from the primary gold deposits (orogenic mesothermal v-, lodedeposits), 

and gold-bearing quartzite's associated-with the 

rocks of the Adola Group and the conglomerates of the Kajimiti 

Beds, that are often confined to Pan-African Shear-Zones and 

Fdts. 

The largest gold placer deposit has been explored in the 

Bore valley with calculated reserves of up to 4.5 tons of gold 

(EMRDC, 1 985; $elas;sie and Reimold, 2000). This placer bas been 

mined since the late 1950s and its gold production is still in 

progress by misd miners. In the Adola area, a total reserve of 

13.67 toas of placer gold was @mated in 1985 (EMRDC, 1985; 

Selassie and ReimoId, 2000). Other placer gold are mined in a 

small scale in Wollega, Akobo 4 Tigray region by local people. 

I '

Mttallic Minerals 67 

Genetically, the gold placers of the Adola area fall in 

three groups. 

(i) residual-eluvial (slope placers) at sites of disintegration 

primary source, (ii) eluvial-alluvial lacers formed in small valleys 

and fans, due to intermittent stre !m activity, and (iii) alluvial 

placers formed in the valley floor and on river ' terraces. 

Commercially, the potential of the area is linked with the alluvial 

placers containing the bulk of the estimated reserves. Residual- 

eluvial and proluvial placers are targets for hand mining 

operations. The major part of known placers is shallow-lying with 

overburden being as thick as 20 m (e.g., Kajimiti). 

Based on the mode of occurrence and geology of placers of 

the area, the following observations can be madel-the low-order 

valleys are rather monotonous in geomotphic aspect along their 

~~3 

entire length. The Iarger valleys (such as Bore, Kajimiti, ,-, + .-. 

Bedakessa, Awata, and Mormora) have contrasting morphologies 

at different sections due to locd control by undetlying geology, . . 

neotectonics and faults. LOW-or& valleys have no terraces. 

Terraces of high-order valleys as a rule have little or no surface 

expression in topography. In most cases the terraces are buried 

under slope waste. 

All placer gold occurrences are discontinuous; they form 

isolated grounds and pay-streaks. Gold is concentrated as nests and 

as combination of nests and pay streaks. Nest-like concentrations 

most frequently occy against distributed gold. 

-- 

Tn conclusion, the regional distribution of placer deposits 

and occurrences in the area is characterized by distinct spatial 

association with both the Megado and Kenticha primary gold belts. 

This emphasises the intimate spatial association of the areas of 

placer formations with the primary gold fields. The majority of the 

placers are localised in the areas of enhanced erosive 

transformation of the relief. Structurally the Adola area consists of 

numerous, variously uplifted blocks of the crystalline basement.

68 Minerat Rcsouwcs Potential of Ethiopia 

Under these circumstances, the spatial distribution of zones of 

'weakness exerts direct control on the formation of the drainage 

pattern. These zones of weakness include systems of faults of 

various ages. 

Figure 1 1 Ground sluicing for placer gold by artisanal miners in Adola area

Figum 12 Placer gold minhg by hydra monitor at Ula Ulo, 

Adnh p i n l r t h Ethjnniq 

Figure 13 Excavating gold-bearing grad in Aodok area

I 

Figure 16 Plawrgoldminiihm adoeppit(34m) by artisanal 

mima {Adola) 

3.2 Platinum deposit 

' Occurrence 

Platinum and palladium are precious metals generally found in 

ultramafic rocks. The source of platinum and palladium deposits is 

ultramafic rocks which have enough sulfur to form a sulfide mineral 

while the magma is still liquid. This sulfide mineral (usually 

pentlmdite, pyrite, chalcopyrite or pyrrhotite) gains platinum by 

mixing with the bulk of the magma because platinum is chalcophile 

and is, concentrated in sulfides. Alternatively, platinum occurs in 

association with chromite either within the chromite mineral itself 

or within sulfides associated with it. 

Sulfide phases only form in ultramafic magmas when the 

magma reaches sulfur saturation. This is generally thought to be 

nearly impossibIe pure fraction& crystalliaation; so other 

processes are usually required in ore genesis models to explain 

sulfur saturation. These include contamination of the magma with 

crustal material, especially sul fur-rich wall-rocks or sediments;


magma mixing; volatile gain or loss. Often platinum is associated 

with nickel, capper, chromium, and cobalt deposits. Platinum is often 

fbund as native platinum and alloyed with iridium as platiniridium. 

The platinum arsenide, sperrylite, is a major source of platinum 

associated with nickel ores in the Sudbury Basin deposit. The rare 

sulfide mineral cooperite, (Pt, Pd, Ni) S, contains platinum along with 

palladium and nickel. Cooperite occurs in the Merensky Reef within 

the Bushveld Complex, Transvgal, South Africa. Platinum, often 

accompanied by small amounts of other platinum family metals, 

occurs in alluvial placer deposits in the Witwatersrand of South 

Africa, Colombia, Ontario, the Ural Mountains, and in cemin western 

U.S. states (Wolfe, 1984). Platinum is produced commercially as a 

by-product of nickel ore processing in the Sudbury deposit. The huge 

quantities of nickel ore processed makes up for the fact that pIatinum 

is present as only 0.5 ppm in the ore. 

Applications 

Platinum, platinum alloys and iridium are used as crucible materials 

for the growth of single crystals, especially oxides. The chemical 

industry uses a significant mount of either platinum or a platinum- 

rhodium alloy catalyst in the form of gauze to catalyze the partial 

oxidation of ammonia to yield nitric oxide, which is the raw materiel 

for fertilizers, explosives, and nitric acid. As a catalyst in the catalytic 

converter, an optional componem of the gasoline-bled automobile 

exhausts system. As a catalyst in fuel cells. Certain platinum- 

containing compounds are capable of crosslinking (or alkylezting) with 

DNA and are chemotherapeutic agents owing to this capability. E;or 

example, cisplatin, carboplatin and oxdiplatin belong to this class 

of drugs (Boyle, 1987). Platinum is also used in. resistance 

thermometers, electrodes for use in electrolysis, grills (deuorat ive 

plates on the teeth) and as a catalyst in the curing of silicone 

elastomers.

Platinum deposits in Ethiopia 

Mcmllic Minrrals 73 

Mineralized mdc-ultramafic rocks in Ethiopia occur as zoned 

Alaskan-ts ultramafic bodies (e.g. Yubdo), ophiolitcs (e.g.. 

Kenticha) and possibly as xenoliths or dikes within the Trap basalts 

covering most of the highlands (Mogessie et al , 2000). 

Linear bodies of altered mafic-ultramafic rocks occurring 

from Yubdo to the Tulu-Dimtu area were thought: to be part of an 

ophiolitic sequence by Kazrnin ef al. (1 978). Recently, Mogessie ef 

al., (2000) have suggested that these rocks were intruded into a 

magmatic rift or back-arc basin. The main rock units of the Yubdo 

area are dunites at the core, surrounded by peridotite and 

hornblende-clinopymxenite; an outcrop pattern typical of Alaskan 

type deposits. 

The Kenticha belt in the Adola granite-greenstone terrain is 

dominated by ulmmafic rock6 with subordinate amphibolites, 

biotite schists, n~inor graphitic schists, and marbles, Based on 

geological field relations, geochemical data and PGElchondrite 

normalized plots, the Kenticha ultramafic rocks are considered to 

be ophiolites (Mogessie et a/., 2002). Detailed ore reflected 

microscope and electron microprobe analyses of chromite rich 

layers within the Renticha rnafic-ultqafic units have been made. 

PGM's such as laurite (RuS2) with a composition varying between 

R~32.390~ 

I -71 h0.61 S62.12 and RUZ~ 

99 @I 5 1 Iro.70 S65.42, and ~rflall 

concentrations of Rh and Pd have been documented for the first 

time. In comparison to the Yubdo m&c-ultramafic rocks, the 

Kenticha ultrarnafics are rich in chromite suzd the small PGM 

grains are most of the time located at the rims of zoned chromite 

grains in contact with chlorite andfor serpentine. Furthermore. 

most of the PGM in Yubdo are rich in Platinum whereas the 

Kenticha are enriched in Ru, 0 s and Ir.

74 Mind Rcsourccs Potential of Ethiopia 

Geology of the Yubdo platit~arn deposit 

The Yubdo platinum deposit occurs in Western Ethiopia, 540 km 

west of Addis Ababa. The deposit was discovered in 1923-1924 

and mining started in 1926. The area is underlqin by an ultramafic , 

complex of qmtinized dunite, pyroxenite and peridotite, 

bounded by a metamorphic aureole of molite-actinolite-chlorib 

talc-serpentine, which is locally schistose, and is surrounded by 

metasediments of the Birbir Group. Birbirite appears to be a silicic 

alteration product overlying the dunite. 

The platinum is associated with ultramafic complexes and 

more specifically with the lowemost part of alteration products 

(laiterites) of dunite rocks. The average grade of secondary residual 

ore from Yubdo mine is 0.005-1.31g pt/rn3. At Yubdo mine, the 

average composition of the Pt-Fe nuggets is 79.48% platinum, 

0.49% palladium, 0,75% rhodium, 0.8% iridium, 1.41% 

osmiridium, and 0.49 % gold. The remaining percentage is iron. 

Other metallic minerals include electnun, pentlandite and 

/ chalcocite (Clarke, 1978). 

Recently, Stanley et al, discovered a new platinum minerals 

species Kingstonite, RhjSs, b m the Birbir River, Yubdo District. 

It occurs as subhedrsl, tabular to elongate anh& inclusions in a 

Pt-Fe nugget with the associated minerals; fernplatinurn, 

tetraferroplatinum, a Cu-Mng Pt-Fe alloy, and osmium, enriched 

oxide mmmts of osmium, laurite, bwieite, fenorhodsite and 

cuprofhodsite. Past production of Yubdo from 1926 is estirnafed at 

2.7 tons. Pt. Resource calculations vary in a wide range between 2 

and 27 tons Pt, following vario& estimates: 20 tons Pt at 0.4 glm3 

by Duval Corp. (1969); 12 tons Pt at 0.34 glt byr Nippon Mining 

Co (1974) and 27 tons Pt at 0.2 dm3 (+ 10 tons Au and 9.8 tons 

Ag) byr Gilevich (1 980). 

There are several localities in Ethiopia where mafic- 

ultramafic rocks occur. me Tertiary Trap Mts which.cover most 

of the highlands of Ethiopia me also interesting locations to look

Metallic Minwala 75 

for mineralized zones. A det&iIed geological, geochemical and 

'ecomic gmlological studies of these mcks will undoubtedly 

result in finding economic precious metal deposits as is the case in 

Yubdo. PGM occurrences have dso ken reported together wjth 

gold from se~eral secondary type occurrences in Western Ethiopia 

(WolIega) (e.g. Dalleti, Tulu Dimtu, residual and Soddu. placer). 

Similar occurrences bve been found southwest dong the belt in 

the Omo River region. 

As to the origin, Platinum Group Metals (Platinum (Ft), 

Palladium (Pd), Iridium ,(Ir), Rhodium (Rh), Osmium (bs), and 

Ruthenium (Ru)) have g$etic &mities to both Ni-Cu-sulphides 

and chromiies. However, while the fundammtal processes 

involved in the formation of mi-Cu and chromite deposits are 

relatively simple, the concenktion and depodtion of PGM 

appears to k a not too well understood, dverst and multistage 

process. S evd lines of evidence indicate that PGM can: 

- Fractionated magmatic fluids enriched in PGMS ascending 

under the influence of dipIacement by the cumulus phases; 

- Deposition h m hydrothermal solutions., 

- Sulfide dmplets pass through turbulent convecting magmas 

and scavenge the PGM's from these magmas. Upon 

cooling, the sulfides and suspended crystals sink, giving 

rise to cumulate layers; 

- Contamination of the magma with the coutry mcks 

triggers the precipitation of sulfides and their PGM' s. 

' F 

1 ,,: :$ 

;& >, - 

'--, *sp.: -$ 

g.'i 

Id t. 

I*; 

. ,+"< 

..: 

I... .. 

;,,

7A Mineral Resources Potential of Ethiopia 

Figure 17 -eal sketch map of h YuWo plmum a m 

Ethiopia.(afk ee al. 20021


Pigrrro 18 A) A rnagmtio droplet of FbPe grain In a ohmmite. B) 

Osmium laths IP a WFe grain h n Yubdo (hn, Kebsde ei 

d. 2000)

Meidlic Minerals 79 

potassium fluorotantalate, reduction of potassium fluorotantalate 

with sodium, or by reacting tanhum carbide with tantaIum oxide. 

Tantalum is also a byproduct from tin smelting (Cemy, 1990). 

Applications 

The major use for tantalum, as tantalum metal powder, is in the 

production of electronic components, mainly tantdum capacitors. 

Tantalum electrolytic apitors exploit the natural tendency of 

tantalum to form .a protective oxide surface layer, using tantalum 

foil as one plate of the capacitor, the oxide as the dielectric, and an 

qledmlytic solution as the other plate. Because the dielectric layer 

can be very thin (thinner than the similar layer in, for instance, an 

alm~um. electrolytic capacitor), high capacitance can be 

=hiex& in a. small space. This size In d weight advantage makes 

tantalum capacitors attractive for portable telephones, pagers, 

personal computers, and automotive electronics. 

Tdum is also used to produce a variety of alloys that 

have high melting points, are strong and have good ductility. 

Alloyed with other metals, it is also used in making carbide tools 

fbr ^metal-working equipment and in the production of superalloys 

for jet engine components,' chkical process equipment, nlacleax 

reactbrs, and missile parts (Cemy, 1990), It is ductile and cm be 

drawn into fine wire, which is used as a filament for evqomting 

metals such as aluminium. Because it is totally immune to the 

action of body liquids and is none-irritating, it is widely used in 

making surgical appliances. Tantalum oxide is used to make 

special high refractive index glass for camera lenses. The metal is 

also used to make vacuum furnace parts.

80 Mineral Resources Potentid of Ethiopia 

The Tantalitc deposit in the Kenticha area 

The Kenticha area is located in Southern Ethiopia within the Adola 

gold field. The area belongs to a me-metal metallogenic province. 

the only one so far known in the horn of Africa. From this it 

follows that a comprehensive study of the different minerals and 

rock types of the Kenticha area can provide preliminary evaluation 

of future economic potential. 

The Kenticha rare-metal pegmatite in the Adola area 

was discovered in 1980 by EMRDC during the course of 

preliminary and detailed explomlion. Mining in Kenticha started in 

1991. Since then the deposit has produced a total of 870 tons of 

tantalite concentrates (Ethiopian Mineral Development Sh. Co). 

Production is now running at about 220,000 lblyear of tantaIum 

oxide from weathered pegmatite and alluvial ore (Selassi e and 

Rehond, 2000). In 1 988, preliminary reserves were eval uated at 

25,000 tons of Tantalite ore at a 0.02-0.03 % Taz05 grade and 

hard rock ore reserves are currently under evaluation by Ethiopian 

Mineral Development Sh. Co. In addition to tantalite, Li, Rb and 

Cs could also be commercially recovered in the future from the 

pepatites of the district, especially by selective mining. 

Furthermore, Colwnbo-tantalite concentrates represent a complex 

raw material for the extraction of other rare metals [e-g. Nb, Zr, 

and REE). Other significant tantalite occurrences have been 

identified in Kilkile, and Bupo, in the same rare-metal field, while 

a Nb-Ta and REE - Th pegmatite-related occurrence close to a two- 

mica granite was discovered near Meleka (Glenso) in the Sidamo 

region. 

The existing geological investigations and the hi story of 

similar pegmatite fields in the ,world suggest the possibility for 

further potential economic me-metal resources within the region. 

Tantalum is reported to be present mainly in eastern Africa and 

southern Afiica such as in Ethiopia, Nigeria, Congo, Burundi, 

Rwanda, Uganda, Tanzania, Zimbabwe, Mozambique, Namibia,


and South Africa. Substantial quantities of tantalite pegmatite 

north of South Africa have started to be- mined in March 200 1. Of 

all these occurrences, remarkably the richest tantalite deposit, more 

than 70% of Ta205, is so far known to be present in E!hiopia 

(Solomon and Zerihun, 1 996), 

Geology af the Kentichi frmntollam-besuing pegmatite depmit 

The rare metal occwrences in Kenticha are hosted in a long ma 

Ihw Kenticha belt. The Kenticha, belt extends for over 100 lun 

[from Katawhicha Mountain on the south to the left bank of the 

Genale River on the north). The pegmatites in the Kenticha raremetal 

field are genetically related to dome- and lens-shaped 

differentiated granitic and pegmatitic intrusions along a discrete N- 

$ fault and shear system, including biotite granite, two-mica 

granite and daskitic granite. The granitic pegmatite, emplaced by 

intruding the ultramafic suite, oc~urs within a large serpentinite hi11 

, that covered about 9 km2. m 

These post-orogenic intrusive are supposed to be h"e^ parent 

rocks of the rare-metal enriched pegmatites occurring within the 

field, mged in zonal patterns around the source granite and 

following a N-S trending regional fault and shear system. The 

post-tectonic granite, =-metal bearing pegmatites and accasional 

alaskitic granite are widely developed in the fom of stock or dikes 

varying from sevd kilometers to a few meters in width. N-S 

trending structure is believsd to have controlled the localization of 

the rare metal bearing pegmatite and associated acidic granitoid, 

The army of pegmatites follows N-S trending find&. In addition to 

the principal N-S trending faults, there are two younger faults 

systems trending NESW and NW-SE. The intersection of these faults 

with those trending N-S appears to be the most favorab1a site for the 

emplacement of the late stage diffemhtes conbhq 

concentrations of the memetal ores (Solomon and Zerihun, 1996).

J 

I, 

i 

< 

f 


'The Iate to post-Pan-ecan Kenticha pegmatite' is dated 

480*50 and 5 1 5k 1 0 Ma (Selassie and Reimold, 2'000): Within athe 

granite-pegmatite system, post-magmatic alterations (albithtiw 

sericitization, greisenimtion, kaolinization and development of 

maimsite and microcline) are widely developed, priicularly in the 

late products of granite-pegmatite series. 

The mineral associatiods found in the pegmatite rocks 

include Columbo-tanlite group minerals, ixiolite, beryl, 

lepidolite, staurolite, phosphates (apatite, arnblygonite and 

lit hiophilbte), tourmalines (schorl and elbaite), garnets (spessartite 

and rnanganian aimandine), rutile, ilrnenite and magnetite 

(Solomon and Zerihun, 1996). Othe me metal occurrences were 

found in Kenticha, KatawHicha, Dermidm, Ula Ulo, Kilkile, 

- 

B U and ~ Kotisa. Detailed investigation of the rare metal bearing 

pegmatite within the main Kenticha deposit has proved a world 

class ore reserve of tantalite with subordinate niobium, lithium, 

beryllium kuhg minerals, gemstones (beryl, spodumene, 

lepidolite, amazonite, mountain quartz) in addition to high quality 

ceramic grade quartz-feldspar and other industrial minerals. The 

complex ore is associated with a primary granite-pegmatite body 

and to a lateriti~ mantle of weathering developed over the primrrry 

pegmatite. In general three typs of ore of the deposit have been 

recognized. 

- Primary ore, tmtalite bearing granite-pegmatite with 

complex Ta-Nb-Li-Be mineralization; 

- Lateritic type ore, th~ mantle of weathering developed 

over pegamtitie and granite; 

- Eluvialdelwial and alluvial placer, 

The weathered ore developed over the primary ore of pegmatite 

represents the huge rare metal resources of the Kenti* deposit. 

This deposit is marked with high quality Ta-Nb and made it one of

, - 

Figure 22 Kdnticha Tantalito deposit with lodon of open pit, 

pht, waste dm$ and tailing dam. 

Metallic Minerals 83

84 Mineral Resources Potential of Ethiupia 

F ~ L r J a i m u r. e. w (black) in quartz and mixdine (white) 

in Kenti& 

Fwm 24 betvlfeen d y h g qmthh and underlyii 

IqnWiteat Keaticha

Figw 26 Mining fnr caatalite in Kmtidm 


rn

Figure 28 Tantslite promsing plant; separation of fm bntdih concentr- %m 

hmbysltaking*@ntih)

d. fieId .umbhs s series of' barren to rrlre 

'&&%&"

88 Mineral Resourn Potential of Ethionia 

The granite body is elongated in north-south dimtion with a 

lenticular shape which has 10.5 lun length and 2 km kidth. It is 

sunounded bi a swarm of pgmatites &at include the above san 

types. The didbution of all the above pegmatite bodies follows a 

zoning pattern around the source granites in which the more complex 

and fractionated ones are located relatively fix hm the centre (e.g. 

Main Kenticha and Bupo I pegmatites) (Figure 30). 

Each zone contains pegmatites of similar geological, geochemical 

and structutal characteristics. The individual zones with pe&tes 

of similar composition, mineralogy and texture are descri&d &low: 

~lbite+pwlumene type (Bupo lpegmatite) is found very far hn the center of the source area and the pegmatite M e s in this zone are 

hly diffe~ntiatsd. This gegqatite is about 12 km north of the 

win Kenticha pegmatite and is deeply affected by weathering. -. 

use of the weathering effect and lack of god exposure, it is less . 

ed and, therefore, mineral association and intend . 

structure are not well known. However, analyses of some '::; 

obtained from 1a-e mistant outcrops, suggest that this '. 

pegmatite body is rich in Ta and probably belongs to the albite- - , 

spodumene type of Cerny's (1990) classification. ji 

C~mplex spodumeue type (Main Kenticha pegmatite), , this ) - I 

wnesponds 

;- 

to the mplex spdumene type described in Cerny's 

p-,t 

(1989; 1990) classification. The pegmatite in this zone is completely 

%r 

differentiated, since each one has different mineralogicalochemid 

characteristics. ~ 

ery1-colnmbite type (Ta-rich), this type is represented in th 

$a 

rrnidama and Kilkile I areas, located south of Wile 111 and north 

Klkile I1 pegmatites, respectively. The ore bodies in both areas 

m characterized by relatively high-Ta ddization. The 

pegrnatites have variable internal zoning, and can be assigned to the 

highIy evolved type of the beryl columbite p 

) classification.

-WiFrMoaals 89, 

Beryl-columbite type (~a-~oorj, this type includes the pgmtites 

of Kilkile 11, Kilkile I11 and Bupo I1 areas, which cantah beryl, d 

femolumbite. Beryl crystals are of the greenish (aquamarine) type 

and tourmaline is of schorl variety. K-feldspar has a graphic texture 

and sometimes shows a slight albitization. Small d a r bookmuscovites 

form patchy textures in the relatively fresh parts of the 

pegmatite blocks. Generally, the single bodies show the outer 

xenomorphic zone as a thin layer, whereas the main pegmatite unit' is 

mostly formed of muscovite, albite, quark, microcline-perthite 

assemblages. Some pegmati- show also a greisens zone (e.g. 

Kilklie TI pegmatite). The country rocks include serpentinite, talc, 

biotite schist's andor biotite gneiss. 

Barren pegmatit- this type is the nearest to the center of the 

source region and contains barren and simple pegmatites parallel to 

the altitude of the two-mica granite. The majority of these pgmatites 

are located in the westem side. On this side, the b n pgmatites 

reach the foot of the Kilkile 111 (44.5 km away from the tw-mica 

' granite.

SEPI* 3 Km 

0- 

Figure 30 Geology of part of the Kenticha mmetd field showing 

zoning of pegmatites, as well as the location of areas mentioned i 

A: area of bamn pgmatiw: B: area of Kilkile [I. Kilkile 111 and Bupo I1 

pegmatites (bayl-columbite types): C: area of Kilkile 1 and Dermidama 

Mineralogy and internal structure of the pegmatite bodies 

The pegmatite unit in the Kenticha rare-rnetal field consists of a 

multitude of large and small veins and dykes, most of which display 

inward mineralogical and textural changes. The variability of internal 

units and textural complexity increases padel to the degree of lim


pegmatite fractionation. This type of pegmatite zoning and inward 

mineralogical and geochemical change hm border to core zone is 

common in most of the rare rnd pegmatites in the world and was 

interpreted (Yahns, 1 982; Shearer et al., 1987; Cemy, 1990) to be an 

inward crystallization from rim to core from hydrous map. The 

observed types of minds in various zones and the gemhemistry of 

some elements within the pegmatites indicate the fractional 

crystallization in the system. As a whole, the vertical trend of zoning 

in these pegmatites is from K-feldspmrich at the top to Na-feldspar- 

rich at the bottom. Most of the pegmatites with a large number of 

zones consist mentially of a bad dic aplite with m overlying 

microcline-quark-albite zone, followed by a quartz-muscovite- 

albite-spodumene zone. The innermost part of some of these 

pegmatite$ consists of a small lenticular mass that includes greisens, 

Iepidolite and quartz core units. Around the quartz zone, cavities or 

pockets filled with euhedral crystals are common. The most evolved 

, pegmatite so far known in the region is the miin Kenticha pegmatite, 

which shows a variety of intd zoning and replacement 

phenomena The sequence of zoning in this pegmatite consists of a 

border zone, first, second and third intermediate zones, and a core 

zone (formed last). 

The lower border zone (footwall) of the pegmatite is formed 

by W t e granite that grades upWard to aplite. The alaskite granite 

is composed of muscovite, K-feldspar, quartz and albite. Mior 

phases that make part of the above mineral association include 

spessarhe, tourmaline, ilmenite and magnetite. This association is 

completed by the columbo-tantalite and Mn-columbite. The first 

intermediate zone is made up of muscovite-quw-albite-mimcline 

pegmatite. The zone is characterized by a medium-grain texture, 

sometimes with giant Microcline crystals. The second intermediate 

zone is composed of albite, cleaveldte, quark, spodumene, 

microcline and sericite. The characteristic accessory and rare 

minerals include apatite, Li-muscovite, tantalite (Mn), cowbite

...k; *.-, 

92 Mineral Rwurces Potential of Ethiopia ,- > La 

(Mn), amblygonite, beryl and ixiofite. It is characterized by medium- 

to came-grained textwe. The columbo-tmtalite minerals in this zone 

contain more Ta and Nb. Next to this zone, the third intermediate 

zone continues upward with a major mineral assemblage of albite, 

spodumene, ammonite, ambl ygonite, microcline and sericite. The 

awewry and ore minerals in this zone include apatite, Li-mica, 

tanate, topaz, beryl, pollucite and ixiolite. The central zone is 

entirely formed by north-south elongated, discontinuous, Ienticular 

quartz and replacement bodies. The replacement bodies include 

spherical greisens bodies and fine-wed Li-micas, both of which 

replace the microclime-perthite and quartz body, The contact between 

the pegmatite and the serpentinite rock is formed by chlorite, talc and 

rnonoczinic amphibolite (tremolite actinolite) assemblages resulting 

fiom the interaction of pegmatite forming aqueous fluids and the 

county rocks. 

As to the mechanism of formation of the Kenticka raremetal 

bearing-pegmatite-granite in Kentich, a well known and 

interesting feature of ore deposit that are genetically associated 

with granite intrusions is that the origin and composition of the 

magma generally controls the nature of the metal assemblages in 

the deposit. This control is almost certainly related in part to the 

metal endowment inherited by the magma from the rocks that was 

melted to produce it. Where felsic magma is derived from melting 

of a sedimentary or s~~racrustal'~roto1ith 

(termed S-type granites), 

associated ore deposits are characterized by concentrations of 

metals such as Ta, Ce, Rb, Sn, W, U, and Th. Where it is derived 

from melting of order igneous protoliths in the crust (I-type 

granite) the ore association is typified by metals such as Cu, Mo, 

Pb, Zn, and Au. The I-type granites tend to be metaluminous and 

typified by tonalitic (or quartz dioritic) to granodioritic 

compositions, whereas S-type are often peraluminous and have 

quartz-monzonitic to granite compositions. 

r

Metallic M inds 93 

The Kenticha rm-metal pegmatite-granite is typified by 

ore mineral associations such as Ta, Nb. Li, Be, Ce. This mineral 

association is metallogneticall y very significant suggesting that the 

parental rock where feIsic magma derived from melting of 

sedimentary or supracrustal protoits. Further more, studies by 

Solomon Tadesse and Zerihun Desta on whole rock analyses from 

the Kenticha pegmatite granite have shown that an Fe203/FeO 

ratio (useful discriminant between I-type with Fe203M.3 and S- 

type, with ratio Fe2031Fe0

94 Mineral Resources PotenIial of Ethiopia 

chlorine, phosphorus, and sulfur. This highly fluid, aqueous melt 

provided an environment for concentration of chemical elements 

with ionic sizes too great to fit into crystalline structures of major 

rock forming minds; these elements were thus concentrated in 

pegmatite deposits. 

The occurrence of pegmatite corresponding to most 

plutonic rock compositions gabbros, diorites, syenites, anorthosites 

further suggests this possibility. Other pegmatites grade into the 

rocks that surround them and show no intrusive relationships. Such 

bodies may represent material produced by melting (anatexis) 

during metamorphism at high temperatures and pressures. Some 

elements and fluids may be literally "sweated out" of a rock 

complex during metamorphism, well known because it conrains 

crystals of many different minerals. This rock is pushed up as large 

veins of magma that was rich in volatile elements, resulting in 

large crystals, usuaIly surrounded by grantic rocks. 

Pegmatites may be composed of a variety of minerals. 

Terms such as granite pegrn'atite, gabbro pegmatite, syenite 

pegmatite, or names with any other plutonic rock type as prefix are 

used. Compositions in the range horn granodiorite to granite are 

common. Large crystals of quartz, potassium feldspar, sodium rich 

plagioclase, and micas (e.g., muscovite and lepidolite) may be 

abundant. Simple pegmatites contain few, if my, exotic minerals. 

The center zones of complex pegmatites, however, may contain a 

wide variety of minerds such as tourmaline, topaz, garnet, 

spodurnene, scapoli te, ber y 1, apatite, fluorite, zircon, and various 

rare minds, some limited to only a few localities in the world. 

GEM quality stones are sought in such rocks. Elements such as 

tungsten, boron, tantalum, columbium, bismuth, tin, uranium, 

radium, sheet mi&, and sulfide minerals of various metallic 

elements are among substances obtained from pegmatite deposits. 

As to the origin of Tantalum, during fractional 

crystallization, water and elements that do not enter the minerals


separated from the magma by crystalIization will end up as the last 

residue of the original magma. This residue is rich in silica and 

water along with elements like the Lithium, Tantalum, Niobium, 

Boron, Beryllium, Rare Earth Elements, and Uranium. This residue 

is often injected into fractuw surrounding the igneous intrusion 

and crystallizes as a rock pegmatite that characteristically consists 

of large crystals. 

3.4 Nickel (Cobalt) deposit 

Occurrence 

The bdk of the nickel mined comes hm two types of ore 

deposits. The first are laterites where the principal ore minerals are 

sickelifexous limonite (Fe, Ni)OIOH) and garnierite, (a hydrous nickel 

silicate): (Ni,MghSif15(OH). The second are magmatic sulfide deposits 

where the principal ore mineral is pentlandite: (Ni, FebS*. Sulfide type 

, nickel deposits are formed in essentially the same manner as 

platinum deposits. Nickel is a chdcophile element which prefers 

sulfides, so an ultramafic or mafic rock which has a sulfide phase 

in the magma may form nickel deposits. The best nickel deposits 

pre formed where sulfide accumulates, much like in a placer gold 

deposit, in the base of lava tubes or vobanic flows -especially 

kornatiite lavas. 

Origin 

Ni-Cu deposits are the end of a magmatic process known as 

"liquid immiscibility". This process involves the separation from 

the parental magma of a sulphur-rich liquid containing Fe-Ni-Cu. 

Upon cooling, the sulphur-rich liquid produces an immiscible 

sulphide phase (droplets of sulphide liquid in silicate liquid, like 

oil in water) from which minerals such as pyrrhotite (FeS), 

pentlandite (Fe, Nibss, and chalcopyrite (CuFeS2) crystaIize. The 

I

96 Mineral Resources Potential of Etkionia 

sulphide liquids, rich in copper and nickel, are denser, and settle to 

the floor of the chamber, where they form copper or nickel ore. Ni- 

Cu deposits are found in layered intrusions, stocks and ultrarnafic 

sills and flows. The largest deposits are of Archean and 

Proterozoic age. Examples of Ni-Cu deposits include the Sudbury 

orebodies in Canada (layered intrusion hosted), the Karnbalda ore 

bodies in Western Australia (ultramafic flow hosted) and the ore 

bodies in the Thompson District of Manitoba, Canada (ultramafic 

sill hosted). 

Applications 

Nickel is used in many industrial and consumer products, including 

stainless steel, magnets, coinage', and special alloys. It is also used 

for plating and as a green tint in glass. Nickel is pre-eminently an 

alloy metal, and its chief use is in the nickel steels and nickel cast 

irons, of which there are innumerable varieties. It is also widely 

used for many other alloys, such as nickel brasses and bronzes, and 

alloys with copper, chromium, aluminium, lead, cobalt, silver, and 

gold. Nickel consumption can be summarized as: nickel steels 

(60%); nickel-copper and nickel-silver alloys (14%); malleable 

nickel, nickel clad and Inconel (9%); plating (6%); nickel cast irons' 

(3%); heat and electric resistance alloys (3%); nickel brasses and 

bronzes (2%); others (3%) (Jensen and Bateman, 1979). 

Nickeliferous deposits in Ethiopia 

More than twenty nickeliferous occurrences have been identified in 

association with serpentinite bodies belonging to the Adola and 

Kenticha Belts (Adola). One third of these occurrences have been 

explored in detail by pitting and drilling, leading to a reserve 

estimate of 17 Mt of ore grading 1.3% nickel (EGS, 1989). Main 

deposits are located at Ula Ulo (4 Mt at 1.33% Ni and 0.01 % Co) 

and Tulla (6.6 Mt at 1.28% Ni)'(EGS, 1989). Other similar nickel


occurrences have also been reported in Sidamo (e,g, Kilta, 2 Mt at 

1.5 % Ni, Big Dubicha, Small Dubicha, Fulanto, Monissa, Burjiji 

wnd Lolotu). 

All these occurrences are related to ultrabasic rmks, 

metamorphosed to serpentinites, almost entirely altered. These 

serpentinites formed of lizardite and antigorite, with some 

chrysotile stringers, are all enclosed in a "Mo" of talc and bands 

of talc schists, tremolite schists, chlorite schists and actinolite 

schists, ~hl: nickel mineralization, of residual type, is hosted in 

Iaterites capping the serpentinite budies and is apparently mainly 

held in a secondary mineral of the garnierite group (pimelite). The 

average metal contents for unaltered ultrabasic source rocks are 

uneconomical: nickel (0.1-0.3%), cobalt (0.02%), copper (0.998%). 

Impregnations of q d t e with pyrite and cobalt with manganese 

coating have been reported in Kunni valley. Other cobalt mineral 

occurrences have also been reported in the area of Nejo, near Tulu 

Bolio and Tula Gotel (Wollega). 

The origin of the deposits seems to be similar to that of 

silicate deposits in other parts of the world. Nickel concentrates in 

the crystalline lattice of ferrornagnesian silicate rock forming 

minerals such as olivine and pyroxene during the early cooling and 

crystallization history of the magma, in the absence of sulphur. 

Fractional crystallization and cumulative process such as gravityinduced 

settling of these early crystals on the bottom of the magma 

chamber can account for the high nickel and chrome contents in 

mnulative ultramafics. Secondary adchment is attained during 

iqmtinization and weathering. The following are descriptions of 

m e of the beqer known deposits some of which have received 

nore attentioh in recent years.

98 Mineral Resources Potmtial of Ethiopia 

Tub nickel ocrurrences 

The Tulls srrpentinite, one of the smallest (200 x '900 m) of the 

serpentinite bodies, forms a conspicuous sparseIy vegetaa hill 23 

km south of Megado. The serpcntinitc strikes 1 50' and dips 55' W; 

and dip 200-30' east and is ovedain to the west by chlorite schist 

whilst quartzites ae adjacent to the eakt The outcrops are highly 

weathered and fractured. Gakierite,. light aquamitrine to dark 

green, occurs as fdlings in some fiVdcture planes. The 

mineralization has been check& by 27 boreholes showing an 

average of 1.28% Ni content over an average depth of 54 m. The 

prospecting holes in the locality revealed reserves of 6.6 Mt at 1.28 

% nickel (EGS, 1989). 

Uh Ulo nickel oacummaear 

Ula Ulo lies about 18 km SSE of Megado. The mpmtinite is & a 

-4- - 

approximately 1000 x 600 m in outcrop, strike N-S and dip 75'. G:. 

. Altogether 138 test holes totalling h ut 1500 m were dug at llla kc' 

UIo in 1963. Garnierib is prominent in the lower slops of the hill; ,.- 

:. - 

g* 

it occurs- as a fmtw in fillings of soapy appearanGI:. Test holei .; 

revealed a reserve of 4 Mt at 1.3.3 % nickel (EGS, 1989). Another ?I: ', 

! 

Big Dubicba 


Big Dubicha lies 8 h NE of Kibre Mengist. Like many of the 

serpentinite bodies it forms a conspicuous feature, rising above 

adjacent hills and being barren of trees. The serpentinite is 

comparatively well-exposed in numerous outcrops. The strike varies 

between 30 and 50' with dips ranging from 25 to 50' W. A few 

chromite lenses, 2-3 m long and stringers, have ken observed. 

Gmierite mineralization occurs in the usual form of fracture 

filling and dissemination in weathered qntinite. Nine to eight 

holes were sunk in the ldity revealing 1.6 tons 

% nickel (EGS, 1989). 

&&&', . 

,! k


contain numerous fine-grained magnetite stingers ranging @bin 

0.5 to 1.5 cm in thickness, The sqentinite body and talc-chlorite 

rock units are often found to contain small seams of chromik, 

1 -2m wide. Serpentinization, silicification, sericitimtion, ~hlaritizathn, 

actinolization and carbonatiztition are the major alteration 

processes that affected the ultramafic body. The Ni-bearing 

mineral is garnierite. It has been prospected by 386 holes, &y 

in the northern pwt, and the result revealed rewwes of 3.9 Mt 

grading 1 28% nickel (EGS, 1989). 

Figurn 3 l Ibe Kenticha q~tw 

.$hiit:F.mS. 

I;~:, , ,r,~:e;~!; 

I 

L-&;$; A +.dl . .., &&a,":- 

3.5 Iron deposit i;i& 

C 

,--,,1 OccurrenmILI, :-: , , . -.-; ---. .-u- r--.,-,-i,' 

,; .I L.: T??:;.. , -'.. .< , ,-..-- .

- ., , . 

Metallic Minerals 10 1 

[ . ,hickel alloy. About 5% of the metearites similarly consist of ironi 

nickel alloy, Although rare, these are the major form of natural 

*%e~llic iron on the e d s surface. 

. , 

Origin 

Fe-Ti deposits are either "stratifom" or present be injections. 

Many small to medium sized magnetite deposits occur in gablamic 

intrusions, but the really big tonnages occur in the stratiform 

lopoliths. The formation of Ti-Fe deposits may be tentatively 

described as follows: 

Residual maghatic melts generally become enriched in silica and 

water; but certain types of basaltic magmas may become enriched 

h iron,and titanium. The basic plagidase magmas may become 

enriched! in iron and titanium. The basic plagioclase wystallizes 

6rst and Fe-oxides last, the residual liquid may dmh out from the 

mush of plagiochse crystals or, in other words, the plagioclase 

' crystals may float in the upper parts of the high density iron melt. 

By this mechanism stratifel layers of titanomagnetite could be 

foped in between anorthosite on top and peridotite at the base. 

The residual liquid may also solidify without segregation; this 

kuld explain the occurrence of olivine rocks with titano-magnetite 

filling crystal interstices. Finally the iron rich residual liquid may 

become injected into t e overlying consolidated rocks and solidify 

as orebodies; that At the structure of the rook (filter pressing). 

Ti-Fe deposits can be broadly divided into ilmenitehematite and 

titanifemus magnetite deposits, Both types show ex-solution 

Gxtures. The economic vdue of the deposits depends on grade and 

- I.. 

kenability to mechanical ilmenite~~wxide separation. An example 

of an economic Ti-Fe deposit is Lac Tho in the AUwrd lake area 

(Quebec). 

>l


Applications 

Iron is the most used of all the metals, comprising 95 % of dl the 

metal tonnage produced worldwide. Its combination of low cost 

and high sirength make it indispensable, especially in applications 

like automobiles, the hulls of large ships, and structural 

components for buildings. Steel is the best known alloy of iron. 

Production 

Approximately 1,100 Mt (million tons) of iron ore was produd in 

the world in 2000, with a gross Market value of approximately 25 

billion US dollars (Jensen and Battman, 1979). While ore 

production occurs in 48 countries, the five largest producers were 

China, Brazil, Australia, Russia and India, accounting for 70% of 

world iron ore production. The 1,100 Mt of iron ore was used to 

produce approximately 572 Mt of pig iron (Wolfe, 1984). 

Irop deposits ia Ethiopia 

Iron occurrences were identified, in many areas in Ethiopia: among 

others, Wollega (Gordoma, Chago, Worakalu, Dimma, Billa, and 

Tulu Bolale) Kaffa (Mai Gudo, GwmmaIucho, Kurkue, Garo, 

Dombowa, and Melka Sedi), and Tigray (Adua, Enticho). They 

belong to three main types (Table 2). 

(i) Precambrian basic intrusion-hosted Fe-Ti type (Bikild, Melka 

Arba), (ii) banded iron formation (BIF) type occurrences associated 

with Pmambrian fernginow quartzites (Koree, Gordoma, Chago) 

and (iii) secondary laterite and/or gossan-related deposits (e.g. 

Melka Sedi, Garo, Gato, Billa, Gmbo, Gammalucho). 

Among these occurrences with those estimated reserves are found 

in: (i) Wollega: Chago (1.2 Mt, 64% Fe), D h a 

(0.05Mt, 65% 

Fe), Gordona-Korree (0.27 Mt, 63% Fe), Worakalu (0,15 Mt, 62% 

Fe), Belowtuist (2.5 Mt), Katta valley (0.1 Mt, 61 % Fe), Yubdo 

(0.05 Mt, 70.9% Fe); (ii) Kaffw: Garo (12.5 Mt, Melka Sedi (12.5


Mt), Dombova (12.5 Mt), Mai Guda (0.075 Mt, 40% Fe); (iii) 

Sihno: Melka Arba (4.63 Mt); (iv) Tigray: Adua, Axurn and 

Enticho (5 Mt, 30% Fe) (EGS, 1989). 

Other occurrences where total reserves are not yet estimated are 

found. in the localities: Aim, Famasari, Billa, Gambo, Gmbella- 

Dembidollo, GeiqDaleti (Wollega), Assale, Beliga, Chilachii 

I Adi Berbere (Tigray), Bissidimo, Galeti, Kunni, Ujau, Soka 

(Ham), Ghimira Bash, Kurkure, Like (Kaffa). Data regarding 

these mcmences are just preliminary observations not based on 

systematic expioration. The folldwing is a description of the better 

known deposit which has received more attention in recent years. 

Bikilal i&n deposit 

The best known m& Ethiopian iron deposit known to date is the 

recently discovered deposit of Bikilal in Wollega. The deposit is 

hosted in Precambrian meta-sedimentary rocks (feldspar- 

amphiblite schist, quart z-amphi bole schist, quark-feldspar and 

mphibk schist, and marble) intruded by basic-ultrahasic rocks 

and granitoids. The titanifemus iron ore bodies are confined to the 

ultrabasic zone which consists of ore-Mng actinoiite rick dzks, 

olivine ppxenite, met a-homblendite, apatitebearing meta- 

hornblendite and meta-gabbro. The ultrabolsic zone is about one 

kilometre wide and 12 km long. The size of the ore bodies is of 

200- 1 400 rn in length, 2-6 m in width and 200-300 m in depth The 

d o a t ore minds in the Bikilal titanifcmw iron ore deposit 

are magnetite (containing ilrnenite as exsolution lamellae) (40x1, 

iImenite (29%) silicate minerals (about 30%). The most ~ m o n 

accessory minerals are pyrrhotite and pyrite (2-2.5%), apatite 

(0.6%), chalcopyrite and pentlandite (< 1%). Main gangue 

minerds are amphiboles, chlorite and rarely phlogopite, olivine, 

pyroxene and plagioclase. The titanifemus iron OR is chiefly 

compact and disseminated. The Bikifal iron *sit is estimated at


about 58 Mt tons grading 41% total Fe (EGS, 1989). Zones of 

apatite enrichment are currently evaluated through drilling (1 8 1 Mt 

of apatite ore at average grade of 3,5% P205, with 2 1.8 % total Fe, 

(Fentaw and Mengistu, 2000); (Selassie and Reimold, 2000). Apart 

from iron and phosphate, vanadium and titanium are by-product 

metals considered to be commercially worthy using magnetic 

dressing benefication, \ 

The origin of the Bikilal Fe-Ti deposits seems to be similar 

to that of iron deposits in other parts of the world. The deposit is 

typically thought to be dated. to large differentiated intmsiove 

complexes made\up mainly of pyroxenite, hablendits and gabbro 

mplaced in Prpcambrian meh-sedimentary mks. The Fe-Ti oxide 

ore accumulations occur as strati- layers and disseminations 

within the intrusion complexes themselves, or as a more massive, 

higher grade, cross-cutting or dyke-like bodies. This deposit is 

clearly a product of in situ crystal fractionation. Early extraction of 

a plagioclaspdo~ crystaI assemblages results in concentration 

of Fe and Ti in the residual magmas, which crystallize to form 

femgabbm. Titanifemus magnetite or hemo-ilmenite also 

crystallizes with disseminated layers formed by crystal settling 

accumulation on the chamber floor. The more massive discordant 

bodies are considered to be a product of the pressing out (filter 

pressing-the processes whereby the residual magma within a 

network of accumulating crystals in a *ally solidified chamber 

can be pressed out into a regions of lower pressure such as 

overlying non-crystalline magma or fractures in the country rock) 

;, - of an Fe-Ti oxide mineral slurry -the slurry concentrated to form 

an intrusion body often dong the margins of the imgely 

. consolidated gabbm-pyroxinite-hornbIendite complexes or into 

: fkactures and breccias in the host rocks.

Table 5: Iron ore deposit types ofzthiopia 

COMMODITIES 

Fe, Ti, (P) 

Fe 

ORE DEPOSIT 

TYPES 

Ore deposits 

hosted by basic 

intrusions 

Banded iron 

formations (BIF 

pp 

F'e, (Mn) 

Metallic Minerals I as 

Table 6: Major Iron ore deposit of Ethiopia (A,B & C class) 

NO Dewit 

name 

Laterite-related 

and gossan- 

related deposits 

Comm. 

I 

Class 

M.41N DEPOSITS 

(A, B, C) 

(see Table 6) 

Bikilal 

MINOR DEPOSITS 

Melka Arba, Kenticha 

Beliga 2, Chago, 

Bikilal Gordana, Koree, 

-- 

Dombova 

Adua, Entichio Adi 

Melka Sedi, Berbere, Chilachikin, 

Cam malurho, Di mma, Katta, Billa. 

Garo, Gambo, Gato (Mai 

Dombova Guda), Melka Sedi, 

Tulu Bollate 

Tonnage 

Range 

Other 

mmm. 

tong. 

I Bikilal (Fe) Fe 10-16 Mi Fe 

Deposit 

Cu, P h(Au, o ~ Co) , T ' i , N i - ~ ~ 9'30 ~ , ~ ~ develop ' under 

1 

3 

-- "-- 

Galnlnalucho I Fe 

Gara Fe 

Fe 

t 

1 

/ 

" 

C 

- -A 

Mt Fe I CO. 

10 - 100 1 Me.Au,!I NI- 

37 19 7.51 

"- M!Fe .!-..Cob. + .. . 

I: : I M:-z.R 37 39 7.50 

ment 

Prospect 

-- 

Pmsprct 

5 Dombova Fe 1 C 'LiLr i ' Prmpect 

ht 

Status 

,

106 Minwal Resources Potmtial of Ethiopia 

. . 

Table 7: Iron Ore occumce and depits of Ethiopia

108. Mineral Resources Potential of Elhimia 

RESERVE 

35.53 9.07 0.05 Mt, 

62%Fe 

Hematite 

4.48 Mt Mawetire. 

Magnetite 

Hemaire 

Formations 

(81F "Superior I 

stc retared 

dqmii: Au. 

Ag. Zn 

maikdatd 

cH-edqUd5: 

Fc, Mn. Hi-C& 

Aq 

CmwdumS. 

R E Nb. Pt 

-:tYMS, 

MVT. Veins 

tic* 

&qmh: Am, 

Agza 

baepoJitrin 

w w 

-- (Ural ard 

Akbl5ub 

i l d 

dEpositsr Ti. Ft. 

depoails 

kkwuist M i d ZM MI f@mii Firmgimus 

(Wobga) oenm*lro kdk, cpmlzils Au, 

Limiw REE. Pb. Ni. PI

3.6 Chromite 


An iron magnesium chromium oxide: (Fe,Mg)CrzOb is an oxide 

minerd belonging to the spinel gotip. Magnesium is always 

present in variable amounts, also aluminium and iron substitute for 

chromim. Chromite is found in peridotite and other layered 

ultramafic intrusive mks as well as in metamorphic racks such as 

serpentinites. Ore deposits of chromite form as early magmatic 

differentiate, It is commonly associatsd with olivine, magnetite, 

serpentine, and corundum, The vast Bushveld Igneous Complex of 

South Africa is a large layered d c to dtrarnafic igneous body 

with some layers, consisting of 90% chromite making the rare rock 

type chromitite. Chromite is found in Afghanistan, Iran, Pakistan, 

Oman, and Zimbabwe (Boyle, 1987). 

Origin 

,When dense minerals form early in the crystallisation sequence, 

they may sink to nmr the bottom of the magma chamber and 

accumulate. This process is called crystal settling. Such settling is 

aided by a low viscosity of the magma; so crystal settling is best 

developed in basaltic magmas. Chromite is one of the first minerals 

to crystallise hm basaltic melts, and may settle out to form dark 

bands of nearly pure chromite. Stratiform chromite deposits consist 

of laterally persistent chromite-rich layers (a few mm to several m 

thick) alternating with silicate layers. The silicate layers include 

ulb.amafic and d ~ rocks c such as dunite, peridotite, pyroxenite 

vd a variety of others, less commonly gabbroic rocks. 

\ Chromite deposits are the end product of the separation of 

solid phases (Cr-rich spinets, (Fe, Mg) (Al, Cr. Fe) 204) from a 

liquid and their accumulation into chmite-rich layers. The 

pmsses involved in the formation of chromite layers are 

Mional crystallization and gravity settling. Chromite crystallizes 

into mineral grains within the silicate liquid and, because they are

110 Mind Potential of Ethiopia 

heavier than the liquid, they sink to form a cummulate layer at the 

base of the intrusive. They are generally found within bad 

portions of mafic-ultramafic layered intrusions of Archaean ageT 

such as the Bushveld Complex in South Africa. Most of the world's 

chromium ores were formed in this manner by the settling of 

chromite. 

Chromite, used mainly in chemid and metallurgical industries 

(chrome fixtures, etc.), is the chief ore of chromium, but, is also 

used as a refkctory material. 

Chromite mcurrencess h Ethiopia 

Occurrences of good quality chromite me found in Sidamo and 

Wollega. The chromite occurrences in Sidamo are associated with 

serpentinite rocks and we= found in Kenticha (Fig. 32), Metti- 

Gola, hbicha Gudda, Dermidama and Molicha, In these localities, 

the mineral occurs as lenticular bodia and pods with varying grain 

size (medium to coarse grained). M&c and ultrstmafic bodies 

hosting chromite are also found in Wollega. Among these 

occurrences, the most significm is the Yubdo-Ddleti-Tdu Dimtu 

belt where chmite-platinum mineralization is associated. The 

detailed geology and potential economic significance of different 

chromite occurrences have not been studied so far. Therefo~, 

systematic exploration is required to assess the chromite potentid. 1 I 

I 1I

3.7 Manganese deposit 

Occurrence 

Metallic Minerals 1 I I 

Manganese occurs principally as pyroIusite (Mn02) and30 a lesser 

extent, as rhodochrosite (MnC03). Land-based resources are large 

but irregularly distributed; those of the United States are very low 

grade and have potentially high extraction costs (Boyle, 1987). 

South Africa and Ukraine account for more than 80% of the 

world's identified resources and South Africa accounts for more 

than 80% of the total exclusive of China and Ukraine. Manganese 

is also mind in Burkina Faso and Gabon. Vast quantities of 

manganese exist in manganese nodules on the ocean floor (Jensen 

and Bateman, 1 979). 

Applications 

Manganese is essential to iron and steel production by virtue of its 

sulfur-fixing, deoxidizing, and alloying properties (Boyle, 1 979).

112 Mineral Resources Potmtial of Ethiopia 

manganese demand, p~sently in the range of 85% to Wh of the 

total demand. Among a variety of other uses, manganese is a key 

component of low-oost stainless steel formulations and certain 

widely d aluminium alloys. It is also added to gasoline in order 

to reduce engine knocking. Manganese (IV) oxide (manganese 

dioxide) is used in the original type of dry cell Wry, and is also 

used as a catalyst. This element is used to decolorize glass 

(removing the greenish tinge that premce of iron pduces) and, in 

higher concentration, mala violet-coloured glass. Manganese 

dioxide is a brown pigment that can be used to make paint and is a 

wmpnent of natural umber. Potassium permangmwte is used in 

chemistry as a potent oxidizer and in medicine as a disinfectant. 

Manganese phosphate is used for rust and corrosion preventation 

on steel, 

Mangam deposits in Ethiopia 

' The Enkafala area in Tigray (Danakil depression) is responsible for 

the small former Ethiopian ,manganese ore production (about 

40,000 tons of ore from 1958 to 1963). mrves of the Enkafala 

sedimentary Mn deposit are believed to be 75,000 metric tons 

(Getaneh, 1985). The thin manganese layer is interstratified in 

cldc plio-Pleistocene marine sediments, Ore consists of hard 

oxides (psilomelane, pyrolusite) d hollandite. Barium is 1 041 y 

present in tbe ore. Other areas in Tigray where manganese mineral 

occurrences are hown .are Mussley, Beliga, Handeda, Adi 

Berbere, and Adi Chigono. The origin of these occurrences is 

poorly known, some of them being at least partly of secondary 

origin (gossan-type e.g. Mussley, Adi Berbere), The Melka Sedi 

occurrence (Kaffa) is associated with laterites.

Metallic Minalals 1 13 ,. 

3.8 Base Metals (Copper, Zinc, Lead, Molybdenum, and 

Wolfram) deposit 

Copper occurrence 

Copper can be found as native copper in mineral form. Minerals 

such as the carbonates azurite'(~a(~0&(0~) and maiachite 

(CU~CO~(OH)~) are sources of copper, as are sulfid& such as 

chalcopyrite (CuFeSz), bornite (CusFeS4), covellite (CuS), 

chdcocite (Cu2S) and oxides like cupriti: (Cy20). Most copper ore 

is mined or extracted from large open pit mines in copper porphyry 

deposits that contain 0,4 to 1.0 % coppe'. Examples include: 

Chuquicamata in Chile and El Chino mine in New Me&. The 

average 'abundance of copper found within crustal rocks is 

ap~mximately 68000 parts per billion by mass, and 22,000 parts 

per billion by atoms (Jensen and Batman, 1979). 

Copper is found in association with many other metals wnd deposit 

styles. Commonly, copper is either formed within sedimentary 

rocks, or associated with igneous rocks. The world's major copper 

deposits are formed within the granitic porphyry copper style. The 

source of the copper is generally considered to be the lower crust 

or mantle where the granite melt forms. The copper is enriched by 

processes during crystallisation of the granite and forms as 

chalcopyrite -a sulfide mined, which is canied up with the 

@mite. 

Sometimes granites erupt to suface as volcanoes, and 

copper minerdisation foms during this phase when the granite and 

volcanic mks cool via hydrothd circulation. Sedimentary 

. copper forms within ocean basins in sedimentary rocks. Generally, 

this forms by brine discharging-hm deeply buried sediments into 

the deep sea, and precipitating cupper and often lead and zinc

I 14 Mineral Resources Potential of Ethiooia 

sulfides directly onto the sea floor. This is then buried by further 

sediments. Often copper is associated with gold, lead, zinc and 

nickel deposits. 

Applications 

Copper is used extensively in products such as: Electronics 

-copper wire, electromagnets, electrical machines, especially 

electromagnetic motors and generators, electrical relays, electrical 

busbars and electrical switches, vacuum tubes, cathode ray tubes, 

and the magnetrons in microwave ovens, wave guides for 

microwave radiation. Household Products +opper plumbing, 

doorknobs and other fixtures in houses, roofing, guttering, and 

rainspouts on buildings; in cooking-wares, such as fiying pans; 

most flatwares (knives, forks, sp~ons) contain some copper (nickel 

silver); sterling silver, if it is to be used in dinnerware, must 

contain a few % copper; copper was sometimes used by the Inuit to 

make the cutting blade for ulus; coinage -as a component of coins, 

often as cupronickel alloy, Euro coins contain different copper 

alloys; biomedical applications: as a biostatic surface in hospitals, 

and to line parts of ships to protect against barnacles and mussels; 

chemical applications: compounds, such as Fehling's solution, have 

applications in chemistry, as a component in ceramic glazes, and to 

colour glass; others: musical instruments, especially brass 

instruments and cymbals (Guil bert and Parks, 1 986). 

Lead 

Occurrence 

Native lead does occur in nature, but it is rare. Currently lead is 

usually found in ore with zinc, silver and (most abundantly) 

copper, and is extracted together with these metals. The main lead 

mineral is galena (PbS), which contains 86.6% lead. Other 

common varieties are cerussite (PbC03) and anglesite (PbS04).

,3 

I 

MetallicMinerals 115 

I But more than half of the Iead used currently comes from recycling 

I (Hutchison, 1983). 

Applications 

Lead is a major constituent of the Lead-acid battery used 

extensively in car batteries. Lead was used as a white pigment in 

Lead paint. It is used as a colouring element in ceramic glazes, 

notably in the colours red and yellow. Lead sticks were used as 

pencils, but has been replaced by graphite for the last 450 years. 

The element is used as projectiles for firearms and fishii sinkers 

because of its density, low cost verse alternative products and ease 

of use due to relatively low melting point. Lead is used in same 

candles to treat the wick to enswe a longer, more even burn. Lead 

is used as shielding from radiation. Molten lead is used as a 

coolant, e.g. for lead-cooled fast reactors. Lead glass is comprised 

of 12-2Ph lead. It changes the optical characteristics of the gIass 

' and reduces the transmission of radiation. Tetraethyl lead has been 

used in leaded fuels to reduce engine knocking; however, this is no 

longer common practice in the Western World due to health 

concerns. Lead is used as electrodes in the process of electrolysis 

(Gilbert and Parks, 1986). 

Origin 

Lead-zinc deposits are generally accompanied by silver, hosted 

within the lead sulfide galena or within the zinc sulfi& sphalerite. 

LRad and zinc-deposits are formed by discharge of deep 

sedimentary brine onto the sea floor (termed sedimentary 

exhalative or SEDEX), or by replacement of limestone, in skarn 

deposits, some associated with submarine volcanoes (called , 

volcanic-hosted massive sulfide or VHMS) or in the aureole of 

subvolcanic intrusions of granite. The vast majority of lead and

I 

I 

I 

I 

1 16 Mineral Resoumm Potential of Ethiopia 

zinc deposits are Proterozoic in age. The immense Broken Sll, 

Century Zinc, Lady Loretta, and Mt Isa deposits in Australia, the 

Sullivan, Red Dog qd Jason deposib of North America and the 

Hindustan zinc ~ l&i t ~h&a are all SEDEX type deposits. 

The limestone replacement type of deposit exemplifies the 

Mississippi Valley Type (MVT). Some of these occur by 

Metallic Minemls 1 17 

water colours or paints, and as an activator in the rubber industry. 

As an over-the-counter ointment, it is applied as a thin coating on 

the exposed skin of the face or nose to prevent dehydration of the 

area of skin, It,can protect against sunburn in the summer and 

windburn in the winter. Applied thinly to a baby's diap area 

(perineum) with each diaper change, it can protect against mh. As 

determined in the Age-Related Eye Disease Study, it is part of an 

effective treatment for age-related macular degeneration in some 

cases. Zinc chloride is used as a deodorant and can be used as a 

wood preservative. 

Zinc production 

There are zinc mines throughout the world, with the largest 

producers being Australia, Canada, China, Peru and the U.S.A. 

Mines in Empe include Vieille Montagne in Belgium, Tara in 

Ireland, and Zirzkgruvan in Sweden (Guilbert and Parks, 1 986). 

Moly bdeaum 

- Occurrence 

Though molybdenum is found in such minerals as wulfenite 

(PbMo04) or powellite (CaMoQ), the main commercial source of 

mo jybdenum is mo lyklenite (MoS2). Molybdenum is mined 

directly, and is also recovered as a by-product of copper mining, It 

is present in ores from 0.01% to about 0.5%. About half of the 

world's molybdenum is mined in the United States, with Phelps 

. Dodge Corporation being a primary provider (Guilbert and Parks, 

1986). 

Applications 

Over % of all molybdenum is used in alloys. Molybdenum is used 

to this day in high-strength alloys and in high-temperature steels.

1 18 Mineral Resources Potential of Ethiopia 

sp&ial molybdenum-containing alloys, such as the Hastelloys, me 

notably heat-resistant and corrosion-resistant. Molybdenum is used 

in oil pipelines, aircraft and missile parts, and in filaments. 

Molybdenum finds use as a catalyst in the petroleum industiy, 

especially in catalysts for removing organic sulfurs from petroleum 

products. Ma-99 is used in the nuclear isotope industry. 

a Molybdenum ranges are pigme'nts ranging from red-yellow to a 

in paints, inks, plastics, and rubber 

Coppr, zinc, lead, molybdenum murmnees in Ethiopia 

Copper most promising occurrences seem to be related to 

volcanogenic massive sulphide (VMS type) mineralization 

occurring in the meta-volcano-sedimentary belts of Western 

Ethiopia (Abetselo, KatPr). Other occurrences are related to basicultrabasic 

magmatic rocks and copper is also a common pathfinder 

of gold in many shear-zone related "mesothermd" goId deposits 

(Table 2). The well-hown Cu-Mu-(Co) Chercher deposit in 

Eastern Ethiopia, hosted in Mesozoic sandstones discordant over 

the Precambrian basement belongs to the Red Bed type. Recently, 

the Ethiopian Mineral Development Sh. Co. have discovered 

copper occurrencm at localities Wachile and G d e in Arero 

Wore&, Borena zone (Southem Etbiopia). The copper minerds 

are malachite associated with meta-granite and &randorite. The 

localities are currently under intensive gmIogical and geophysical 

mmm 

Zinc, Lead, as well as other commodities (e.g. Ag, As, Sb, Bi) are 

associated with Cu and Au in polpetallic massive and 

disseminated sulphides of volcanogenic and volcano-sedimentary 

deposits (Kata, Abetselo, Azale-Akendeyu), as well as pathfinders 

y primary "lode" orogenic deposits. Other Pb or Pbs 

located close to the basal contact of discordant 

I 

i 

II

Metallic Minds 119 

sediments over the Precambrian bament (e,g+ Soka, Ijabq 

Ramis River in Wolfega and AfFmtu and Grava) may represent 

Red Bed type or carbonate-hosted base-metal deposits. This type 

of mineralization warrants further investigations. 

I 

Molybdenum (as molybdenite) occurs in leucocratic quartzplagioclase 

acidic rocks at a flank of granite batholiths at Fakusho. 

Some granitic pegmatites also contain Mo (Bissidimo valley, 

Chiltu). Wolfram occurs with Mo in granitic rocks at Kata 

(Wollega); this element is also commonly identified as trace 

dement in numemu shear-zone related mesothermal gold deposits 

(e.g. Digati, East SWo, and Korkora in Adola), Other 

molybdenum occurrences have been reported in Bissidimo River 

valley 13 km hm the town of 'Ham. The Mo is associated with 

quartz veins. The quartz veins confining Mo mineral occurs in 

pegnmites. Similar occurrences has been also found in Dedessa 

River (Wollega) associated with pegmatites, The scarcity of 

si-cant base-metals deposits in Ethiopia may k due to a lack of 

systematic exploration. Therefore, systematic exploration is 

required to asses the base-metals potential of the country. 

Molybdenum, Tin, and tungsten 4 s generally form in a 

certain type of granite, via a similar mechanism to intrusive-related 

gold and copper. They are considered together because the process 

of fuming these deposits is essentially the same. Skarn type 

mindisation related to these granites is a very important type of 

tin, tungsten and molybdenum deposit. Slam deposits form by 

reaction of minedised fluids from the granite reacting with wall 

rocks such as limestone. S h mineralisation is also important in 

lead, zinc, copper, gold and occasionally uranium minerahation. 

Greisen granite is another related tin-molybdenum and 

topaz mineralisat ion style. Greisens are formed by endoskam 

alteration of granite during the cooling stages of emplacement. 

Greisen fluids are formed by gyanites as the last highly gas- and

120 Mind Reuwrces Potential of Ethiopia 

water-rich phases of complete crystalisation of granite melts. This 

fluid is forced into the interstitial spaces of the granite and pools at 

the upper margins, here boiling and alteration occur. 

3.9 Radioactive mineral (Uranium, Thorium) deposits 

Udum is a naturally occurring element found in low levels 

witkin all rocks, soils, and water. This is the highest-numbered 

element to be found naturally in significant quantities on earth. It: is 

considered to be more plentiful than antimony, beryllium, 

cadmium, gold, mercury, silver, or tungsten and is abut as 

abundant as arsenic or molybdenum. It is found in many minerals 

including waninite (the most common uranium ore), smite, 

uranophane, torbernite, and coffinite. Significant concentrations of 

~miwn occur in some substances such as phosphate rocks, and 

minerals such as tantalite, lignite, and monazite sands also contain 

uranium-rich ores (It is recovered commercially from these 

sources) (Jensen and Bateman, 1979). The decay of uranium, 

thorium and potassium40 in the Earth's mantle is thought to be the 

main source of heat that keeps the outer core liquid'and drives 

mantle convection, which in tub drives plate tectonics. Uranium 

ores, i.e. mks containing uranium mineralisation in concentrations 

that can be mined economically, typically give I to 4 pounds of 

uranium oxide per ton, or 0.05 to 0.20 % uranium oxides. 

Origin 

Uranium deposits are usually sourced from radioactive granites, 

where certain minerals such as monazite are leached during 

hydrothermal activity or during circulation of groundwater, The 

uranium is brought into solution by acidic conditions and is 

deposited when this acidity is neutralized. Generally, this occurs in 

certain carbon-bearing sediments, within an unconformity in 

sedimentary strata. Uranium has a large atom that does not "fit"

1 

Metallic M inds 121 

into most silicate structures, and is therefore concmtmted in the 

magmatic fluid afier most of the magma has crystallized, where it 

enters the structures of h n and sphene in granites and 

pegmatites. For economic deposits of U minerals to form, U has to 

be leached out of its host rock, mobilized, then redeposited, as is 

the case with vein deposits. Alternatively, the concentration of U 

has to reach a high enough level in the residual fluid of magmatic 

crystallion, that U mineral can crystallize directly out of the 

magmatic fluid and will occur disseminated in granites and 

pegmatites. 

Applications 

The 6 use of urttnium in the civil sector is as fuel for 

commd nuclear power plai~ts. Generdly, this fuel is in the 

fom of enriched uranium, which has been processed to have 

higher-h-nad levels of 235~, sacient to be used for a 

variety of purposes relating to nuclear fission. Commercial nuclear 

power plants use fuel typically enriched to 2-3% 235~, though some 

reactor designs (such as the Candu reactom) can use natural uranium 

(unenriched, less than 1% 23S~) fuel (Jensen and Bateman, 1979). 

Radhdve 'mined accurm- in Ethiopia 

Radioactive mineral deposits of economic class have so far not 

ken discovered in Ethiopia Uranium and thorium minerals have 

been o h e d in pegmatite veins occurring in gneisses of 

Hararghe and Sidamo (Kenticha) regions. Precambrian granite, 

Cretaceous and Jurassic sediments in the same regions, particularly 

in the Din Dam-Ham district, are also gonsidered to be 

fsvourable host rocks for the deposition of radioactive minds. 

The scarcity of significant radioactive mineral deposits in Ethiopia 

may be due to a lack of systematic exploration.

:In lMi&raI Rwufces Potential of Ethiopia 

' ' .# 'Udutn deposits are usually s o d hm mdioaatiNe 

&mites, where ceitain minerals such as monazite are "l~~hed 

i &king hydrothermal activity or during circulation of groundwW~ 

The 'uranium is bmlight into solution by acidic cohditions and is 

de~sitetl when this acidity is neutralised. Generally, this aurs h 

i 

I o&ain carbon-bearing sediments, within an wmnfbmity in 

; 

; 

i 

I 

1 

se'd&ent&y strata The majority of the world's nuclear power is 

murced,hm h u m in such deposits. 

Ilmenite (FeTi03) is a d y magnetic iron-black or steel-grey 

minerd found in metamorphic and plutonic igneous racks. it is an 

ironithim oxide in crystalline form. The majority of the 

ilme'hite mid is used as a raw material for titanium oxide, which 

is mainly-twd for titanium pigment production (paper, paint, 

plastics, rubber, printing inks, cosmetics, soap and phamceuticals). 

' 

The titanium dioxide is an extremely white substance used as a 

base in high quality paint (~enseh and Bateman, 1979). 

The gabbroic intrusive rocks,af Melka Arba and Bikilal areas are 

important hosts of ilmenite. Tlmenite is fomd intimately associated 

with magnetite, hosted by ~dissmbted ore-bring pyroxenite 

andlor hornblmdEte8 and massive iron ores. The average grade of 

henite for disseminated ore-bearing pyroxenite and iron ores at 

Melka Arba area. is 9.100/0 and 17.80% respeotively (Mengistu and 

Fentaw, 2000). \

Chapter 4 

Industrial minerals 

Industrial minerals and rocks are a group of naturally mcurring 

materials excluding gemstones, metallic ores, groundwater and fuels 

(coal, oil and gas) that are important sources of raw materials for the 

chemical, metallurgical, construction, agricultural, and related 

industries. A few metallic ores such as chromite, alumina, and 

pyrolusite, when used for certain purposes such as refractories in high 

temperaturn furnaces, may also be classified as industrial minerals. 

Industrial minerals are commonly occurring minerals and 

rocks that aE widely used in industry, sometimes undergoing very 

little processing. Most are high volume and low unit value 

commodities and their economic importance depends on the 

availabi 1 ity of markets, market location, transportation costs, their 

' physical and che~nical characteristics, and the degree of processing 

required for end use, A notable feature of these minerais and racks is 

that a single material may form the basis for a wide range of 

industries, starting from low technology processes producing low 

value products to higher technology industrial units producing high 

value products for export markets (McVey, 1989). A developing 

country with abundant resoumes and little know-how may start by 

producing low unit value products for the home market, followed 

eventually by high value products for export markets. A good :,: 

example is provided by a resouFe like limestone or dolomite which *r . 

initially may be a source of construction material (cement, aggregate 

and dimension stone) and later a raw material for agricultural, 

metallurgical, and chemical industries. Earnings from foreign trade r! 

could be increased by limiting exports of unprocessed raw materials. 

For example, a government may decide to export less phosphate rock 

while increasing exports of phosphoric acid and phosphatic fettilizers. 

How much effort and money is needed to catalog national industrial 

minerals and rock is a difficult, costly, but not impossible task, 

, ' 

'

124 Mineral Resourm Potential of Ethionia 

Groups of Industrial Minerals 

Industrial minerals may be classified based upon different factors; 

on end-use and economic factors. One classification identifies the 

following six groupings: construction materials, ceramic materials, 

metallurgical and refractory materials, abrasive materials, general 

manufacturing materials, and chemical and fertilizer materials. 

These six categories can fall into three broad groups. The 

first group, known as construction materials, includes sand, gravel, 

clays and stone (e-g., limestone, dolomite, granite, serpentinite and 

quartzite), Stone is both a source of crushed and dimension stone. 

This group is characterized by materials that are valued for their 

physical attributes, are very widespread in nature, are very bulky, 

and have low unit value, even as they require minimal processing 

before use. These attributes have a profound effect on the 

economic value of industrial mineral deposits. Commodities with 

high bulk and low unit value must be located close to markets to be 

economic, while less common materials with unique properties 

have a high unit value and may be profitably sold at high prices i 

distant markets (McVey, 1989). i 1 

The second group, referred to as process materials, includes 

a wide range of minerals and rocks possessing special 

characteristics that allow them to be used in specialized areas. This 

group includes (i) ceramic materials made up mainly of clays but 

also silica, limestone, dolomite, feldspar, quarts and bauxite; (ii) 

abrasive materiqls like garnet, silica, and especially chalcedony, 

chert, quartz, quartzite, sandstone, and silica sand; and (iii) 

rehctory and metallurgical materials like magnesite, fire clay, 

graphite, bauxite, silica, and dolomite. Materials in the third group 

include optical materials like quartz; -absorbent materials like 

bentonite and diatomite; fillers like asbestos, bentonite, gypsum, 

kaolin, limestone, and vermiculite; glass materials like glass sands, 

soda ash, limestone, dolomite, feldspar, borax, and gypsum; and oil 

drilling materials fke asbestos: barite, bentonite, limestone and

Industrial Minerals 125 

dolomite. Materials in this group are valued mostly for their 

physical properties. They are less bulky, have higher unit values 

than construction materials, and can be sold on the export market. 

Industrial mineral deposits in Ethiopia 

Industrial mineral resources occur in various geological formations 

from Precambrian to recent and are used in a wide set of industries; 

among them, glasses, ceramics and cement industries are 

prominent. The main comrnadities available in large quantities in 

Ethiopia include soda ash, potash, diatomite, bentonite, clay, 

common salt, gypsum, anhydrite, feldspars, talc, kyanite, 

mgnesite, dolomite, graphite, quartz, mica, apatite, pumice, silica 

sand, kaolin, phosphate, and silica. Despite the availability of 

these industrial mineral resources, Ethiopia used to import raw 

materials to supply existing local industries. 

4.1 Soda ash (sodium carbonate) 

Sodium carbonate (also known as washing soda or soda ash), 

NA~CO~, is the anhydrous sodium carbonate. The most common 

sodium carbonate is heptahydrate, a crystalline substance which 

readily efloresces to form a white powder, the monohydrate. The 

best sodium carbonate known form is sodium carbonate 

decahydrate. Soda ash has a cooling alkaline taste, and can be 

extracted from the ashes of many plants. It is often produced 

artificially in large quantities from common salt but, commercial 

soda ash, is extracted from lake brines or the mineral trona World 

soda ash production for 2003 was estimated at 38 million metric 

tons (McVey, 1989). Of the 3 1 countries that produce natural and 

synthetic soda ash, the United States was the world's largest 

producer, accounting for 28 % of total world output. Only the 

United States, Botswana, China, Ethiopia, and Kenya produce soda 

ash from natural sources -the remainder manufactures soda ash

126 ~in&al Resources Potential of Ethiopia 

through various chemical processes, primarily the Solvay synthetic 

soda ash +prpdwtion process. Total world natural soda ash. 

production reprebented abut 31 % of combined (bath natural md 

synthetic) world sdda ash production, The five leading producers 

were the United stab, china, Russia, India, and Germany, 

accounting for 71 % of world production in 2003 (McVey, 1989). 

Applications 

I Domestically it is used as a water softener during laundry. It 

competes with the ions magnesih and calcium in hard water and 

* prevents them b m bmding with the detergent bein4 used. Without 

using washing soda, additiqnal detergent is needed to soak up the 

magnesium and dcim iqns. Colled washing soda in the detergent 

section of Ares, it effectively removes oil, grease, and alcohol 

stains. Sodium carbonate is kidely used in photographic pmcesses 

as a pH igulator to main* stable alkaline conditions necessary 

for the action of the majority ,of developing agents (McVey, 

1989). Sdum carbonate is also used by the brick industry as a 

wetting agent to reduce tho amouni of water needed to extrude the 

clay. sodium carbonate is used in the mmufmtm of glass, pulp 

and paper, detergents, and chemicals such as sodium silicates and 

sodium phosphates. It is also used as an alkaline agent in many 

chemical industries. 

Soda mh depib in Ethiopia 

The Ethiopian Rift Valley Lakes, particuiarly, Lakes Abiyata and 

Shala, contain huge volumes of tmna brines (460 Mt of sodium 

carbonate in solution, at concentmtions ranging between 1.1 and 

1.9 % (Mengistu and Fentad, 2000). Soda ash deposits are 

localized in major volcano-tectonic depression (calderas) filled by 

lacustrine deposits. Prolonged evaporation is responsible for the 

ation in concentrations. Lake Shalla and Chitu have high

Induslrid M i d 127 

concentration of alkali elements in solution. Lake Abiyata alone 

has revealed the presence of 400 Mt ofMnes of soda ash (EGS, 

1989). In this locality, 25,000 tons of brines are produced annually 

by a small scale pilot plant. Abiyata Soda Ash Enterprise produced 

6,444 tons of soda ash in 2004 compared with 4,377 tons in 2003.- 

The company was conducting a feasibility study on the 

construction of a new processing plant with a capacity of 1.2 

Mtlyear. Subject to favorable results of the study; a first-stage 

plant with a capacity of 220,000'1/year would be built (Hariman, 

2004). 

4.2 Diatomite 

Diatomaceous earth, also known as diatomite, kieselguhr, 

kieselgur, and celite, is a naturally occurring, soft, chalk-like, 

sedimentary rock mineral that is easily crumbled into a fine white 

to off-white powder. This powder has an abrasive feeling similar to 

puhice powder and is very light-weight due to its high porosity. It 

is made primarily of silica and. consists of fossilized remains of 

diatoms, a type of hard-shelled algae. It is used as a filtration aid, 

as a mild abrasive, as a mechanical insecticide, as an absorbent for 

liquids, as cat litter, and as a component of dynamite (McVey, 

1 989). The most common use (68%) of diatomaceous earth is as a 

filter medium, especially for swimming pools. It has a high 

porosity, because it is composed of microscopicall y-small? coffin- 

like, hollow particles. It is used in chemistry, as a filtration aid, to 

filter very fine particles that would otherwise pass or clog filter 

paper. It is also used to filter watek and other liquids, such as beer. 

It can also filter syrups and sugar. Other industries such as paper, 

pints, ceramics, soap and detergents use it as a filling material.

I28 Mind Resources Potential of Ethiopia 

Occurreltlce 

Because diatomite forms from the remains of water-borne diatoms, 

it is found close to either current or former bodies of water. It is 

generally divided into two categories based upon soqrce; 

freshwater and saltwater. Freshwater diatomite is mined+om dry 

lake beds and is characteristically low in crystalline silica wntent, 

Salt water diatomite contains high crystalline silica content, 

making it a useful material for filters, due to the sieve-like feams 

d 

of the crystals (Noetstaller, 1988). 

Applications 

Diatomite is used as filler (paint, pulp, rubber, pharmaceuticals, 

etc), toothpaste, and polish- 

Diatomite depits In Ethiopia 

' 

Most of the diatomite depofits are located within the MER and the 

A k depression and more than 12 diatomite occurrences have been 

identified by EGS. Deposits of relatively good quality are found in 

Gade Mota, Adamitulu, Chefe Jilla and Abiyata located in the 

central part of the rift, The high-grade ores in the above localities 

have Si02, A1203, F-O3 and CaO in the range of 84.=6.5%, 3.1- 

3.7a0, 1.5-2.4%, and 0.1-1 .Ph, ~spectively (Mengistu and 

Fentaw, 2000). The diatomite deposits are located in lacustrine 

deposits of Tertiary to ~lejstoeene age, interbedded with 

volcaniclastic rocks, ignimbrite, t@-and pumim, Total geological 

potential- of the Lakes Region District (Mota, Adamitulu, Chefe 

Jilh and Abiyata) is estimated at $0 Mi of diatomite of which 

about 85% is contributed by Gade Motta diatomite (EGS, 19891, 

These--d,eposits have Si02, Al2O3, FezOs and CaO in the range of 

84,S86.$0/'0,

43 Bentonite 


Bentonite is an absorbent aluminium, generally impure clay 

consisting of phyllosilicate mostly of montmorillonite, (Na, 

Ca)3(Al,MghSi40 dOH)z*nH20 with several other types. Two 

types exist: swelling bentonite, which is also called sodium 

bentonite, and non-swelling bentonite or calcium bentonite. It 

forms h m weathering of volcanic ash, most often in the presence 

of a water body. Bentonite expands when wet-sodium bentonite 

can absorb several hundred % of its dry weight in water 

(Noetstaller, 1988). 

Applications 

It is commonly used in drilling fluids. used to make slurry walls, 

and to form impermeable barriefs (i.e. plug old wells, as a linerin 

the base of landfills to prevent migration of leachate into the soil); 

several other minor uses (medicine, agriculture, etc.) also exist. 

Bentonite is used as absorbent, animal. feed, foundary sand, 

catalyst (oil refining), waterproofing and sealing, etc. (Noetstalier, 

1988). 

Bentonite deposits in Ethiopia 

Huge deposits of bentonite occur in the Afar region at several sites 

(e,g. Wakisa Mi, Gewme area, Hararghe) and at Gidicho Island 

(Lake Abaya) in Sidarno. In the Afar region, the total resources 

have been estimatsd at 170 Mt of bentonite (EGS, 1989). The 

chemical composition is in the range of 5040% silica, 11-14 % 

alumina, 7-9% iron and less than 1.3% sodium and potassium 

(Mengistu and Fentaw 2000). The deposits are part of the thick 

sequence of lacustrine and reverine clays, silts sands and 

calcareous grits, grad conglomerates and Mites interbedded with 

basalt and ash beds. The sediments were deposited near the 

western margin of the southern part of Afai Depression which

1 30 Mineral Rqmm Potential &Ethiopia 

throughout are late Tertiary and Quaternary. The largest deposit h 

situated about 17 km north-east of the town of Gewane (lati* 

10~14' 30"N and longitudes*40~ 35'40"E and #*35'30"~) 

mupying an area of 6.5 km2. The reserves at this site have been 

estimated at 77 Mt by EGS. The average thickness of the bentonite 

cl L y is about 13.8 m. The second largest deposit is Wolrseisa 

si ted 1-3 krn north of DessisAssab highway been the 

Badona River and Warseisa. The bentonite deposit occupies an 

area of about 127 ktn2. The reserves have been athated to be 

over 7 Mt and the average thickness is about 5.6 m. 

The Ledi deposit is situated dong the Addis-Assab 

highway about 30 km south of the Dessie junction, It is bounded 

by latitude l.lO1O'OO"-1 1'1 3'20" and longitudes 40~42'00'"- 

40°47~". In the area, east and west of the highway, the clay is 

calculated to outcrop over an area of 557,000 m2. At Ledi, the 

average thickness of the bentonitic bed is estimated to 3.2 m and 

, reserves have'been calculated to 1.78 Mt; the total reserves in the 

&a-have been estimated to 7 Mt (Mengistu and Fentaw 2000). 

Much-higher-qdity deposits of bentonite Rave been found 

at Lake Abaya in Sidamo. ~ hk 'bentonite-bearing beds are part of 

lacustihe sediments, which consist of clays, salt-bearing beds, 

sandstones, calcareous sandstones, conglomerates aud interbedded 

volcaniclastic rocks, They result, following Mengistu and Fentaw 

(20001, fiorn the dieration of glassy magmatic materials. The 

s in the ~idioho Island (Lake Abaya, Rift Valley) are 

ed to be 6.4 Mt (EGS, 1989). 

-4 Other clays and kaolin 

Clay deposits are formed h m the weathering of feldspar bearing 

ocks, such as granites, pegmdtes, gneiss or sandstone and 

olcanics, volcaniclastics and sediments. Kaolin results from the 

weat hering of granite and gneiss feldspar-related rocks and from

alteration (hydrothermal and weathering) of felsic and intermediate 

volcanics and volcaniclastics. 

Kaolinite is a mineral with the chemical composition 

A12Sif15(0H)+ It is a layered silicate mined, with one tetrahedral 

sheet linked through oxygen molecules to one octahedral sheet of 

alumina mtahedra, It is a soft, earthy, usually white mineral 

(doctahedral phyllosilicate clay), produced by the chemical 

weathering of feldspar, Natural deposits of kaolinite mixed with 

other clays and silica, are known as lraolinite or china clay, In 

I !many parts of the world, it is coloured pink-orange-red by iron 

oxide, giving it a distinct rust' hue. Lighter iron concentrations 

i 

! yield white, yellow or light orange colours. Alternating layers are 

? sometimes found, as at Providence, Canyon State Park, in Georgia, 

r: 

P . 

I 

I' 

. 1 

@ 

USA (Noetstaller, 1988), 

' Kaolinite is one of the most common industrial mifierclls, it is 

mined in Brazil, France, Britain, Germany, India, Australia, Japan 

(Amakusa), Chin% and the South-eastern U.S. states of Georgia, 

Florida, and, to a lesser extent, South Carolina (Hmben and Bates, 

r 984). 

Applications 

LI-,, 9Due to its extremely fine nature (her than silt), it is mixed with 

'water and transported in tanks as a liquid slurry. It is used in 

8, ceramics, medicine, bricks, paper, as a food additive, in toothpaste, 

' and in cosmetics. A recent use is as a specially formulated spray 

applied to fruits, vegetables, and other vegetation to repel or deter 

d damage. A traditional use is to soothe an upset stomach, 

similar to the way parrots (and lam, hums) in South America 

1; originally use it. The largest use is in the production of paper, as it 

is a key ingredient in mating 'glossy' pap (but calcium

, 

Kaolinldepwits in Ethiopia 

Refractory bond. clays and clays suitable for cement manufachuing 

occur, in Gonder (Chelga) and Shewa (Koka). Alluvial clay 

deposits for brick, tile, pottery and pipe industry occur in Shewa 

(Addis Abah w), near Debre Zeit, Akaki, Kaliti and Suhlw 

between Debre Sina and Debre khan, and Zega W&l, Ka& 

(Bebeka), Adola (Kibre Mengist ma), Wollega milla), Hararghe 

(Dire Dawa area), Abay River Valley and the Rift Valley Lake 

Regions. The main sources of kaoIin for the ceramic industries are 

the weatbering products of granites and pegmatites. Clay materials 

for the manufacture of pigments occur in Gondar and Kaffa. 

Ceramic clays are common in Ambo, Shewa, Harar arid Adola 

(Bombowha or Bombweha). According to Mengistu and Fentaw 

(2000), Kaolinite is the predomimt clay mineral of the 

Kombolcha (Harar) and Bombowha (Adola) areas with quartz- 

&Idspar and illite/muscovite occuring as subordinate minerals, 

Alumina is generally above 35% in the Bornbowha kaolin with 

,impurity elements such as iron (< 1%) and total alkali rind titanium 

accounting for less than 3%. On the contrary, the Kombdcha 

kaolin bears a relatively lower alumina (33.24%), and higher total 

alkali and iron, averaging 2.54% and 2.63% respectively. Reserves 

of kaolin at Bombowha are edhkd to over 0.5 Mt (EGS, 1989). 

The Bombowha kaolin mining is supplying the main ceramic raw 

materid to the oniy one ceramics factory of Ethiopia, known as 

Tabor Ceramics Factory, located in Awassa, south Ethiopia. 

Kaolin is an mential constituent of cups, saucers, plates, including 

ather porcelain wares including porcelain electrical insulators, In 

recent years, domestic output of kaolin and sulfuric acid has been 

inhibiid by limited domestic demand: caustic soda, by import 

competition and shortages of lime need& as raw material: and

silica sand, by the capacity of the country's only glass and bottle 

factory. 

4.5 Common salt 

Sodium chloride, also h wn as common salt, table salt, or halite, 

is a chemical compound with the f'omuIa NwCI, Sodium chloride 

is the salt most responsible for the saliity of the ocem and of the 

extmelhdar fluid of many muiticellular organisms. As the main 

ingredient in ediblesalt, it is commonly used as a condiment and 

food preservative. Sodium chloride is essential to life on earth. 

Most biological tissues and Imdy fluids contain a varying amount 

of salt. The concentration of sodium ions in the blood is dkdy 

related to the regulation of safe body-fluid levels. Propagation of 

nerve impulses by signal transduction is regdated by sodium ions. 

(Potassium, a metal closely related to Sdium, is also a major 

component in the same bodily system). 0.9% sodium chloride in 

water is called a physiological solution because it is isotonic with 

blood plasma It is known medically as normal saline moetstaller, 

EvapmOn of lake water or sea water results in the loss of water 

, and thus conceatrates dissolved substances in the remaining water. 

When the water becomes saturated in such dissolved substance 

they precipitate hm the water. Deposits of halite (table salt), 

gypsum (used in plaster and wall board), borax (used in soap), and 

sylvite (potassium chloride, h m which potassium is extracted to 

use in fertilizers) result from this process.

134 Mineral Resources Potwial of Ethiopia 

Applications 

Whik most people are familiar with the many uses of salt 'in 

cooking, they might be unaware that salt is used in a plethora of 

applications, from manufactwing pulp and paper a d dyeing 

textiIes and fabric to producing soaps and detergents. In most of 

Cam& and the northem USA, large quantities of rack sdt are used 

to help clear highways of ice during winter, although "Road Wtn 

loses its melting ability at temperatures blow -1 5°C to -20°C 

(5OF to 4OF). Salt is a h the raw material used to prodchlorine 

which itself is required for the production of many 

modern materids including PVC and pesticides used in human and 

animd diet, food seasoning and food presewations, to prepare 

sodium hydroxide, soda ash, cawtic soda, hydrochloric acid, 

chlorine; metallic sodium in ceramic glazes; metallurgy, cuijng of 

hides, mhmd wafers, soap mufwcture, home water softeners, 

highway de-icing, photography qnd in scientific equipment for 

optical parts. Single crystals are used for spectroscopy, ~Itraviolet 

and inhd transmission. 

Rock salt is produced hm the Danakil depression, which covers w 

dace of many thousands of square kilometres with reserves 

estimated at 3 Mt of salt (Getaneh, 1985). Common salt occurs 

both as brine and rock salt. Rock salt commonly occurs as thin 

stratified layers; gmerally less than one meter thick assaciated 

with marl and gypsum beds. 

Many salt water sources are exploited far salt in saIines 

which are located in Bale (e.g. Kalamis, Otrada, Creen, Dol, 

Hocdu, Eldere), Gojjam (50 km south-east of Debre Markm) and 

Sidamo, near Mega (e.g. El Sod). Ogaden, Afar and Sidamo me the 

most potential source areas. The potential salt resources of Afar 

are Bu&,Gekim, Afdm and Assale arm. The resources are

&ted at ksevd. hundnL million .tons wjlh,.a:jgqde; af = 

NiCl- The Afdera.salt plain done has a xwmwue. offatma 3% 

million tons (Magistu and Fentaw 2QQO). mer. minor somw 

imlude dty springs o~~ from wldc. cl.aters ia-many 

subordinate ponds of Afder, Ed, =me, eta, in: the Southm 

Ethiopia and munt for a small portion of artisanal mining of 

edible salt. Afar Salt plc, Bashenfer Sdt plc, and Gea A&on

136 Mineral Resources Potential of Ethio~ia 

fireproofing, fire extinguishing compositions, cosmetics, dusting 

powder, and toothepaste. Other applications are*-as filler material, 

smoke suppressant- in plastics, a -reinforcing agent in neoprene* 

rubber, a drying agent, and calm retention in floods. In addition, 

high purity magnesium wbonate is used as anti-acid and as an 

additive in table salt to keep it free flowing (Noetstrlller, 1988), 

Magnesium carbonate, most often referred to as 'chalk', is used in 

rock climbii as a drying agent for hmds. 

\ 

Magmesite deposits in Ethiopia 

wesite is found with dolomitic marble in Kenticha (Adoh 

Belt), as white, fine to medium grained crystalline rock. lt occurs 

-as linear belts extending for tens of kilometers. It is mainly 

associated with graphite schist. The width of the occurrence varies 

from few meters to about 50 m. Other occurrences of magmite 

me reported in H m (k Jak, Kunni), Sidamo, Moyale, 

WoIlega and .Assom in close 'on with basic and ultrabasic 

EGki rocks as yeins; ,Systematic e=n activities are required to 

assess the ecummic :potential of the magnesite mmmnces.

I FIm 33 Magtmite block from ~h magnosite deposit in of K4cb Adola 

4.7 1 Feldspar (ceramic and sheet glers raw materials) 

1 Feldspar is the m e of an important group of rock-forming 

minerals which make up perhaps as much as 60% of the Earth's 

crust. Feldspars crystallize b m magma in both intrusive and 

extrusive rocks; they occur ssLcompact minerals, as veins, and are 

also present in many types of metamorphic rock. Rock formed 

entirely of plagioclase feldspar is known as anorthosite. Feldspars 

are also found in many types of sedimentary rock. This group of 

minerals consists of framework or tectosilicates: 

orthoclase a potassium-aluminium silicate; 

microcline also a potassium-aluminium silicate; and

138 M i d Resoutces Potential of Ethiopia 

plagioclase a sodiutpdtqidum silicate to.: a-cdq 

aluminium silicate isomorphous ' sdb: 

oligoclase, andesine, labradorite, bytownih, d d . 

Feldspar is a common raw material in the production of ceramics; 

feldspars are used for thennoluminescence dating and optical 

dating in earth sciences and mhaeology; feldspar is an ingredient 

in Bon Ami brand household cleaner; it is used as a glazing 

material. Feldspar is also industrially important in glass and 

cemic industries; patter and enamelware; soaps; bond for 

abrasive wheels; mrnen@ and insulating compositions; fertilizer; 1 

tarred roofmg materials; and as a sizing, or filler, in textiles and 

paper. A warsg greyish-gkn talc has been called soapstone or 

steatite gql @# been used for stoves, sinks, electrical switch 

boards, e&m:(%hy, 1989). 1 

Feldspar deposit in ~thiopia 

- 

Feldspar occurrences have been reported in a number of localities tij 

in Ethiopia, the most irnportaAt of which are in Sidamo (e.g. 

;,p 

Kenticha and Neghele) and Hmrghe (Babile-Bombasa). 6- 

Generally, in all of these localities, feldspars are associated with 

pegmatite dykes. The feldspar mineral is of microcline or albite 

type, The mserves in the Kenticha pegmatite deposit have been 

dm&d to 0.46 Mt (Ethiopian Mineral Development Sh. Co) and 

the pegmatite dykes in Babile-Bombasa contain abossible reserve 

of 0.15 Mt of feldspar (EGS, 1989). Presently !he feldspar useful 

for industrial application in Ethiopia comes from the Kenticha 

pegmatite which is produced ss'bypmluc't to the primary tantalum 

concentrate mining. The feldspar in Kenticha pegmatite usually 

forms large pure white crystals with intergrowth of quartz and 

qodumene.

4.8 Talc 

Occurrence 

Industrial M inds 139 

Talc is a mineral composed of hydrated magneim silicate with 

the chemical formula HzMg3(Si03)4 or Mg3Si401dOHh, It occm 

as foliated to fibrous masses, its monoclinic crystals being so rare 

as to be host unknown. It has a pfect b d cleavage, and the 

folh are non-elastic, although slightly flexible, It -is sectile and 

very soft, with a hardness of 1 (t'alc is the softest of the Mohs' scde 

of mineral hardness). It has a pific gravity of 2.5 -2.8, a waxlike 

or pearly luster, and is translucent to opaque. Its colour ranges h., 1:: 

133 

from white to grey or green and it has a distinctly greasy fed and 

its streak is white. 

Applidions 

Talc finds use as a cosmetic (talcum powder), as a lubrimt, and as 

fdler in paper manufacture. Talc is used in baby powder, an 

astringent powder used for preventing rashes on the area covered 

by a diaper (Nmtstdler, 1 988). - 

Ta.k deposits of Ethiopia 

Talc minedimtion is widespread in Sidamo (Negele, 

Agremariam, Uh Ul, Shakisso, Megado, kenticha, Moyele 

greenstone belt, and Tulia), Tigray, and in many parts in Wollega 

(Yubdo). The talc deposits are generally of two types: those 

occuring in schists and those associated with serpentinite rocks. A 

resource of about 0.1 Mt of talc has been identified at Anno, 80 km 

north of Kibre Mengist in Adola (Mengistu and Fentaw, 2000). For 

all that, however, there has been no systematic investigation on talc 

for commercial purposes. Hence, dudy is recommended to make 

the best of such important resources of the country. 

-

' b~ k, alternative 

I 

140 Mineral Rtsou- Potential of Ethidpia 

4.9 Kyanite 

Kyanite is a typically blue silicate mineral, commonly found in 

aluminium-rich metamorphic pegrnatites and/or sedimentary rock. 

Kymite is a diagnostic mineral of the Blueschist Facies of 

metamorphic rocks. K yanite is a member of the duminosilicate 

series, which includes the polymorph andalusite and the 

polymorph sillimanite. Kyanite is strongly anisotropic, in that its 

hardness varies depending on its crystallographic direction. While 

this is a feature of almost all minerals, in kyanite this anisotropism 

can be considered an identifying characteristic. Kyanite has several 

names, including dirthcnc, rnunkrudite and cyanite. 

White-grey kyanite is also cdled heticite (Noetstaller, 1988). 

Applications 

Kymite is used primarily in pfractory and ceramic products, 

including porcelain plumbing fixtures and dinnerware. It is also 

wed in electrical insulators and abrasives. Kyanite has also been 

used as a gemstone, though this use is limited by its anisotropisrn 

and perfect cleavage. Finally, as with most minerals, kyanite is a 

collector's minerztl. i1 

Kyanite deposits in Ethiopia 

The north-eastern part of the AdoIa Belt hosts a thin belt of 

kyanite-quartz schist and kaolinized kyanite-quartz mica schist 

extending for more than 30 km; modal compositions of these 

kyanite-bearing rocks range between 21-26 % kyanite, 7 1-75 % 

quartz and 2-5 % other minerals. In the Chembi area, detailed 

mapping and geologic inference by Fentaw and Mengistu, suggest 

a resource of more than I0 Mt of high quaIity kyanite. The Chembi 

kyanite is hosted by quartz-kyanite schist having a regional strike 

direction of nearly N-S for more than 30 km and dipping at about 

20' to the east. Keolitlized quartz-kyanite-mica schist occurs as

~ 

.. - 

Industrial Minerals 

.. 

14 1 

intercalation within the quart z-kyanite schist. Graphite schist, 

amphibole schist, quartz-kyanite schist, quartz-feldspathic schist, 

and granitic intrusive characterize the area. Quartz and kyanite 

constitute about 95% of the bulk mineralogy with kaolin, 

illite/muscovite and naile occudng as subordinate minerals. 

4.10 Graphite 

Graphite is one of the allotropes of carbon. Unlike diamond, 

graphite is a conductor, ,and can be used, for instance, as the 

material in the electrodes of an electrical arc lamp. Graphite holds 

the distinction of being the most stable form of solid carbn ever 

discovered. It may be considered to be the highest grade of cod, 

just above anthracite, although - it is not normally used as fuel 

because it is hard to ignite. 

Applicaf ions 

Most people first encounter graphite as pencil lead (in fact it is not 

lead, it is graphite). In its pure glassy (isotropic) synthetic forms, 

pyrolytic graphite and carbon fiber graphite is an extremely strong, 

heat-resistant (to 3000 "C) material, used in reentry shields for 

missile nosecones, solid rocket engines, high temperature reacto~s, 

brake shoes, electric motor brushes and as electrodes in EDM 

electrical discharge machines. Imescent or expandable graphites 

are used in firestops, particularly plastic pipe devices, as well as 

gaskets, fitted around the perimeter of a fire door. During a fire, 

the graphite intumesces (expands and chars) to resist fire 

penetration and reduce the likelihood of the spread of fire and 

hes. A typical start expansion temperature (SET) is between 150 

and 300 degrees Celsius. Cartmn fikr and carbon mnotubes are 

also used in graphite reinforced plastics, ad in heat-resistant 

composites such as reinforced carbn-carbn (RCC). Products 

made from carbopfiber graphite composites include fishing rods,

142 Mineral Resourocs Potential of Ethiopia 

golf-clubs, and bicycle frames, and have been successfully 

employsd in reinforced concrete (Noetstaller, 1 98 8). 

Graphite deposits in Ethiopia 

The meta-sedimentary rocks in Sidarno, Haramghe, Wollega and 

Tigray are potential sources for graphite. A series of Iong belts of 

graphitic schist extends for tens of kms through the Kenticha and 

Kibre Mengist areas of the Adola Belt and in Soka, and Kunni 

valley of the Chercher Mountain with large greenschist series. The 

graphite in Moyale area is hosted by quartz-feldsp-mica schists 

and quartzites which gendl y form continuous bodies extending 

for hundreds of meters, The .Moyale graphite deposit has an 

estimated reserve of 0.46 Mt of graphite (Mengistu and Fentaw, 

2000). 

- - 4.11 Silica 

The chemical compund silicon dioxide, also known as silica, is 

the oxide of silicon, chemical formula Si@. Siliceous is an 

adjective meaning "referri6 to silica". Silica is found in nature in 

( aB$; several forms, including quartz and opal. In fact, it has 17 

I . .I' 

crystalline forms. The most oornmon constituent of sand in inland 

continental settings and non-mpical coastal settings is silica, 

usually in the form of quartz because the considerable hardness of 

this mineral resists erosion, However, the composition of sand 

varies according to local rock sources and conditions. Variants 

found in high-pressure impacts are mite and stishovite. Many 

rrns of life contain silica structures (Biogenic Silica), including 

icro-organisms such as diatoms, plants such as horsetail, and 

mds such as hexactinellid sponges. It is present in the cell walls 

virious plants (including edible ones) to strengthen their 

ctural integrity. '

hx several. fum incldiing ;, glass (a 

form is called fwd silica), synthetic 

@I (used e.g. as desiccants in new &Xhes ' 

ca is also -used as a food additive, primarily as a flow 

n.pow;ded foods, or to absorb water (Nogtaller;"l.~IB~ : j f I 

4- 8 - 

.r . . 

occurs in #he .MU@W valley, in 'the Penmaand 

in Enticho units df Adigrdt-Ump of 

rig@$ lk dca d deposits of Enticho area are grouped within 

sediments that form lower part of 

Gnurp. The silica deposits afilhticho Sd~&kf the 

= g&y a t e to grey* 

in* tw,aqpne grained gnd at ~Lors kaolinid The thickness 

oft&md$$pne ranges from IS30 m. Other good quality sand 

is hewn to O& in Eci'ug9 . >< valley* 

7T.T 

qpql* 

,?' 1 . 

- 

' II 

. . 

'.


4.12 Quartz 

Occurrence 

Quartz occurs in hydrothermal veins and pegrnatites. Well-formed 

crystals may reach several metres in length and width hundreds of 

kilometers. These veins may bear precious metals such as gold or 

silver, and form the quartz ores sought in mining. Erosion of 

pegrnatites may reveal expansive pockets of crystals, known as 

"Cathedrals." Quartz is a cpnmon constituent of granite, 

sandstone, limestone, and many other igneous, sedimentary, and 

metamorphic rocks. Trid y mite and cristobalite are high 

temperature polymorphs of SiOz which occur in high silica 

volcanic rocks. Lechaklierite is an amorphous silica glass SiOz 

which is formed by lightning strikes in quartz sand, 

Applications 

Many varieties of quartz are used in jewelry and for ornamental 

purposes. Agate and chalcedony are used in scientific instruments, 

chemical and radio apparatus. Ground and crushed quartz are used 

in wood filler, ceramics, glass, polishing soap and as an abrasive. It 

is also used as a flux in metallurgical work and in making 

refractory bricks. 

Quartz deposits in Ethiopia 

Quartz occurs widely in the basement rocks, in the form of veins 

and as a component of pegmatites. Several quartz vein and quartz- 

bearing pegmatites occur in the Kenticha area, with estimated 

resource of 0.26 Mt (Ethiopian.'Mineral Development Sh. Co) of 

good quality that can be used for glass and ceramics factories.

Itldwtrial Minds 143 

Specific varieties of mica include; biotite, muscovite, lepidolite~@~~ 

phlogopite, illite. Muscovite, also known as potash mica, is a 

phyllosilicate minemi of aluminium and potassium with formula 

KAl2(A1Si3Ol o)(F,0H)2. Muscovite is the most common mica, 

found in granites, pegmatite, gneisses and schists, and as a contact 

metamorphic rock or as a secondary minerd resulting from the 

alteration of topaz, feldspar, kyanite, etc. Biotite is a common 

phyllosilicate minerd whose chemical formula is 

K(Mg,Fe++)3AlSi301 O(F,0H)2 and has a molecular weight of 

+. . 

43 3,53g/mol. kpidolite (KLi2A1(A1, Si)30 lo(F,0H)2) is a lilac or 

rose-violet colored phyllosilicate rriinerd of the mica group that is 

a secondary source of lithium. It is associated with other lithiumbearing 

minerals like spodumene in pegmatite bodies, It is one of 

the major sources of the rare dkdi metals, rubidium and cesium. 

I 

I Puogopite is a yellow, greenish or reddish brown member of the 

mica family of phyllosilicates. It is also known as magnesium

I 

I 

144 Mineral Resourcm IWdd of Ethiopia 

mica. It occurs in contaqt metamorphic zones around intrusives 

into magnesium rich limestones, dolostone, and in WM~ ultmmiic 

igneaus rocks. Illite is a none- clay-sized, mica~eous 

minerd. Illite is a phyllodicate or kyd silicate, Typical 

applications are plastic, paint, jhper, fire extinguisher, insulaters 

mid cosmetics (NoWer, 1988). 

I Mica depmits in Etbiopir 

Mia is known to o q in H m (Jijiga, Cmma, and Asebeteferi); 

Sidamo (Chembi, Mde& and Bornbo,wha) and Wollega ma All 

Imown occmce3 PC 'BSSOC& ~ith pegmatitic veins in the 

.Went rocks. The pegmatites commonly host columbo-tantalite 

group mind, ixiolite, berylJ s&urolite, phosphate (apatite, 

k mblygonite and lithiophillite), tourmaline (&rl and elbaite), 

spodumene, garnet (spessarite and manganian almandine), rutile, 

ilmenite and magnetite. 

4.14 Agwaminerrrls (Phosphritm, potash, Iim~~neldobmite, 

gypsum lanhydrftel suhr, natural zeolite, scoria/ 

pumice) 

! 

Apminerals are minerds of importance to agriculture and 

horticulture, and are usually essential plant nutrients. The study of 

agrominerds is termed agmgeology, and wgrogeologists are 

concerned with issues such as the replenishment of soil fertility in 

r areas where-ggrominerals have been mined out or depleted by 

i unsustaimble farming methods. 

! 4.15 Phosphate 

[ 

Aptite is a group of phosphate minerals, usually referring tb 

hydroxylapatite, fluorapatite, and chlorapatite, named for high 

concentrations of OK, I?, or C1' ions, respectively, in the crystal.

I ndusttial Minerals 147 

The formula of the admixture of the three most common species is 

written as COlj(PO&(OH, F, Cl). 

Applications 

Apatite is one of few minerals that are produced and used by 

biological systems. H ydrox ylapatite is the major component of 

tooth enamel, and a large component of bone material. Fluorapatite 

is slightly stranger than hy,droxyapatite; thus, fluoridated water, 

which will allow exchange in the teeth of hydroxyl ions for 

fluoride ions, slightly strengthens the teeth (Noetstaller, 1 988). 

Origin 

Immense quantities of phosphate rock mur in older sedimentary 

basin, generally formed in the hteromic. Phosphate deposits are. 

thought to be sourced from the skeletons of Dead Sea creatures 

which accumulated on the seafloor. Similar to iron ore deposits 

and oil, particular conditions in the ocean and environment are 

thought to have contributed to these deposits within the geological 

past. Phosphate deposits are also formed from alkaline igneous 

rocks such as nepheline sye&tes, carbonatites and associated rock 

types. The phosphate is, in this case, contained within magmatic 

apatite, monazite or other rare-earth phosphates. 

! Phmphate dapadb in Ethiopia 

Considerable efforts have been made by EGS over the last few 

1 

decades to discover phosphate deposits in Ethiopia. The 

exploration efforts of the EGS showed the potentid of finding 

phosphate accumulations in various geological settings of Ethiopia 

Based on paleo-environmentah and lithologicd considerations 

1 dong with findings from borehole evidence, the late Cretaceous 

(Coniacian-Campmian) rock Series of Eastern. Fthiopia , has great 

I potential for phosphate accumulations. The Upper Cretaceous


represents a phospho-genic period in which many phosphorites 

have been discovered worldkide. Unfortunately, the Upper 

Cretaceous sediments do not crop out at the surface. 

Potential areas in Ethiopia with the greatest chance of 

finding large quantities of sedimentary phosphates are in the 

eastern part of the country, in Tertiary sedimentary sequences 

associated with transgressions and regressions in the Somalia- 

Ogaden embayment. The Auradu sequence in particular has the 

potential of bearing phosphates as these sediments were deposited 

under conditions favourable for phosphate accumulation. These 

characteristics include a favourable palmgeographic setting, cyclic 

transgressive-~gressive sequences, a typical chert-limestone-marl 

association and deposition during a major phosphogenic time 

interval, the Eocene. Other potential areas for finding phosphates 

are the carbonatite-peralkaline ring structures of Cenozoic age. 

To date, phosphate mineral resources in Ethiopia (Wollega, 

= Bale, and Borena areas) are related to intrusive rocks. Layered 

gabbro, gabbro-pyroxenite, and alkaline gabbro plutons host 

apatite-ilmenite mineralization. The gabbroic intrusions of Bikilal 

( Wollega) and gabbro-pyroxenite rocks emplaced in the basement 

rocks of biotite-amphibole gneisses and quartzo-feldspathic 

gneisses of Melka Arba are currently regarded as the most 

promising potential phosphate resources. Apatite, ilmenite and 

magnetite are the main minerals of economic interest in the area. 

Apatite is mainly hosted by disseminated apatite-oxide-bearing 

pyroxenite and gabbro pegmatites. The ore occurs as lenses and 

interlayering with gabbro and have width ranging from stringers to 

several meters. The average grade of P205 for Melka Arba area is 

about 3.75% (Mengistu and Fentaw, 2000). 

Small amounts of mitridatite, a very rare Ca-Fe-Mn 

phosphate mineral with the formula c%(H~ 0) [(~e* 8.2 

0.8)06(P04)9].3H20 has been found in lacustrine sediments in the 

Shungura Formation near Kelem north of Lake Turkana, in

InaustrialMbemls 149 

southwestern Ethiopia (Rogers and Brown, 1979). These minerals 

mcur together with hydrox y -apati te, following partial dissolution 

of carbonate substituted apatite (fish scales and bones). The latdral 

extent of these lacustrine phosphatic beds is not known, These 

phosphate finds are important as they indicate biogenic phosphate 

mineralization in a lacustrine rift-related environment, similar to 

that in which the Minjingu phosphate deposit in the Tanzanian riff 

valley has been found. Other potential phosphorite accumulations 

could be expected in the black shale-chert-limestone associations 

of another major phosphogenic period, the Neopmtemzui~~ In 

Ethiopia these sequences occur in the Tulu Dimtu metasedimentary 

sequence of Wollega region, in the .Adigrat area of 

Tigre region, and in various other geological formations (Assefa, 

1991). 

The Bikilal phosphate deposit 

The only igneous phosphates discovered to date, are at Bikild, 24 

km north-northeast of Ghimbi in Wollega Administrative Province 

and Melka Arba (Sidamo). The phosphate mineralidon is 

relatively unusual, as it is associated with a Proterozoic layered 

gabbro-anorthosite intrusion. Low-grade phosphates (34% P205, 

mean 4.56% P2O5) have been encountered in the apatite-magnetite- 

iImenite mineralization that is spatially and genetically associated 

with the intrusive complex. The apatite-magnetite-ilmenite 

mineralization in hornblendites occurs in a zone about 15 km long 

and 0.7 to 1.2 km wide. Several apatite-bearing hornblendites have 

been delineated in steeply dipping bands. The crystallographic 

unit-cell a-value of the Bi kilal apatites is a = 9.394 A (Abe~y el a/., 

1 994), indicative of a relatively unreactive fluor-apatite. 

Reported reserve estimates of apatite-bearing material in 

the Bikilal area, to a depth of 200 m, are 127 million tones at 3.5% 

P205, 23.8% Fez& 7.3% TiOz (Yohannes, 1994, Mengistu and 

Fentaw, 2000). The phosphate resource in Bikilal which is

IS0 M i d Resources Potentld uf Ethiopia 

composed of apatite, ihenite and magnetite has the following 

compositions and mums: 3.59% PzOs, 6.04% TiOz, 0.09%V205 

and 2 1,87% total iron. The nm-surface, Iow-grade igneous 

phosphates from Bikilal have been evaluated on their suitability for 

upgrading through siezing and magnetic separation (Abera, 1 988; 

Abera et a!., 1994). Apatite concentrates up to 36% P2O5 were 

produced using simple processing techniques. However, the 

recovery rate was low at only 40-5 8% (Abem, et al., 1994). 

4.16 ~y~surn, anhydrite 

Occurrence 

Gypsum is a very common mineral, is thick and extensive 

evaporitic beds in association with other sedimentary rocks. The 

largest deposits known occur in strata from the Permian age. 

Gypsum is deposited in lake yd sea water, as well as in hot 

springs, from volcanic vapors, and sulfate solutions in veins. 

Hydrothermal anhydrite in veins is commonly hydrated to gypsum 

by groundwater in near surface exposures. It is often associated 

with the minerals halite and sulfur. Because the gypsum from the 

quarries of the Montmartre district of Paris has long furnished 

burnt gypsum used for various purposes, this material has been 

called plaster of Paris (McVey, 1989). 

Production 

Commercial quantities of gypsum are found in Germany, Italy, 

England, in British Columbia, Manitoba, Ontario, Nova Scotia and 

Newfoundland in Canada, and in New York, Michigan, Iowa, 

Kansas, Arizona, New Mexico, Colomdo, Utah and Nevada in the 

United States. There is also a large mine located at Plaster City, 

California in Imperial County (McVey, 1989).

Applications 

Industrial Minerals 15 1 

Blackboard chalk, cement, drywall, plaster, a construction 

material, dental modes, surgical casts, paint filler, toothpaste, 

gesso, molds for casting metals, agricultural soil amendment, 

solidifying earth (cast earth construction), tofu coagulation, 

improving mineral content of brewing water, dietary calcium 

additives in breads and cereals, pharmaceuticals, 'dessicant. 

Anhydrous calcium sulfate (anhydrite) is sold under the brand 

name Drierite (Noetstaller, 1988). 

Gypsum, anhydrite deposits in Ethiopia 

Very large deposits of gypsum and anhydrite are known to occur in 

the sedimentary forrf;ations of Danakil depression, Ogaden, Shewa, 

Gojjam (Abay), Tigray and Hararghe. Extensive gypsum and 

anhydrite resources are known from the Mugher (Sodoble) valley, 

the Abay beds, Jemma River, Ferefer, Dewalle, Adi Guddem and 

Hagere Selam. The Adi Guddem and Hagere Selam gypsum has a 

resource potential of about 410,000 tons (Mengistu and Fentaw, 

2000). 

These occurrences are mainly associated with the Mesozoic 

sedimentary rocks and occur at many localities as htercalation 

with calcareous strata. Total reserves are enormous because the 

thickness of the gypsum deposits is many hundreds of metres and 

the formations are known to extend laterally for hundreds of 

kilometres. Gypsum and anhydrite are associated with salt and 

potash at the upper part of the Quaternary evaporites of the 

D&il depression in association with Quaternary salt and potash 

deposits. Others occurrences are hosted by Mesozoic sedimentary 

formations as intercalations within calcareous rocks. Patches of 

gypsum also occur in the lacustrine beds of lower Awash River 

valley near Asaita, in southern Afar region.

152 M i d hums P d a l of Ethiopia 

4.17 Potash (Fertilizer mw materials) 

Potash is an impure form of potassium carbonate (K2C03) mixed 

with other potassium salts. Potash is used as a fertilizer, while the 

pwe carbonate is used in medicine, in the chemical industry and to 

produce decorative colour effects on brass, bronze and nickel. 

Production 

The worId's largest potash producer is the Potash Corporation of 

Saskatchewan (North America). Many other mas, however, have 

the resources for potash production. Today, 14 countries produce 

the world's supply of potash. The main producers are North 

America (mainly Saskatcbewa, with two-thirds of the world's 

recoverable potash located there), Russia, Belarus, Germany, Israel 

and Jordan, (the later two both using solar mporaPion pans at the 

Dad Sea to produce camallite from which potassium chloride is 

' produced). In Ethiopia, some 3,578 short tons and 2,500 short tons 

were mined by small-scale extraction techniqua in 1917 and 1927 

respectively (EGS, 1989). 

Potash deposits h Ethiopia 

There are large potash resources in Ethiopia in the extremely hot 

and arid Danakil depssion near Dallol. The potash deposit is par? 

of a Quaternary evaporite sequence that covers an area of about 

1,150 km2, of which only a small portion has been explored. 

Exploration work by the US-based Ralph M. Pmns Company 

included drilling of more than 300 lmreholes, seismic work and 

shaft sinking to 100 m depths, as well as approximately 600 m 

underground openings (EGS, 1989). The company delineated two 

ore bodies in the Dallol area; the Crescent ore body and the Mudey 

ore body. In this area the evaporite sequence is greater than 1,000 

m thick and includes Iarge potagh reserves. Most of the potassium 

salt is in the form of sylvite (KCI), but carnallite and kainite are

,+ 

Industrial MimlS : -153 977 

also reported. The main sylvite-bearing zone ranges :frop 1 5 

in thiclu~ess. 

Potash reserves are located mainly in th(: ~&il 

depression (Salt Valley). Dallol @anakil) is s niajoi ' d&j&it 

hosting Mite, sylvite, and other potassium salts reserves 

shallow marine evaporitic sediments that also contain gyps&-alnd 

anhydrite. The salt formation is composed of a thick evapohte 

succession of gypsum, anhydrite, inter stratified halite, potash salts 

and shales. New indications surfaced out recently that three 

I borehole were drilled M e r to the east in the Danakil depression 

1 

I 

and encountmd two layers of potash at 680 rn and 930 m and 

presumed to be stratigraphically continues with the Musely ore 

body, Therefore, the total potential reserve of potash within the salt 

plain alone is estimated to reach several billion tons. The tonnage 

of recoverable potash product in the Musley ore zone, based on, 85 

drill hoIes, is 30,021,000 short tons (Arkin 1969). The whole 

a depression contains at least 1 60,456,000 short tons of ore with 3 1- 

34% KC1 (Arb, 1969, Mengistu and Fentaw, 2000). Reserve 

estimates by Abera (1 994) exceed 60 million tonnes of recoved1e 

KCI.

Figure 35 Rock salt in the Danakil Depression worked out by 

traditional miners, Northern Ethiopia 

. 4.18 Dolomite and Limestone 

Dolomlte is the name of both a carbonate rock and a mineral 

consisting of calcium magnesium carbonate (c~tMg(C0~)~) found 

in crystals. Dolomite rock (also dolostone) is composed 

predominantly of the mineral dolomite. Limestone which is 

partially replaced by ,dolomite is referred to as dolomitic limestone, 

or as magnesian limestone. Dolomite mineral crystallizes in the 

trigod-rhombohedd system. * It forms white, grey to pink, 

commonly curved crystals, although it is usualry massive. It has 

physical properties similar to those of the mineral calcite, but does 

not rapidly dissolve or effervesce (fizz) in ilute hydrochloric acid. 

3.5 to 4 and the specific gra&y is 2.8

I 

I 

I 

ApplCcp1tio1~~ 

Indudrial Minerals I55 

Dolomite is used as an omentai stone, as a raw material for the 

manufiadme of cement, and as a source of magnesium oxide. It is 

an important petroleum reservoir rock, and serves as the host rock 

for large strata-bound Mississippi Valley-Type (MVT) ore deposits 

of base metals (that is, readily oxidized metals) such as lead, zinc, 

and copper. Where calcite limestone is uncommon or tcw, costly, 

dolomite is sometime used in its place as a flux (impurity remover) 

for the smelting of iron and steel. In horticulture, dolomite and 

dolomitic limestone are added to soils and soilless potting mixes to 

lower their acidity ("sweeten" them) (Noetstaller, 1 988). 

Dolornitellimestone depits in Ethiopia 

There is several million tons of dolomite as large in quantity as 

limestone is all over Ethiopia. Soil surveys of Ethiopia show that 

. the soils of large areas of western and southwestern Ethiopia are 

acid, with pH levels below 5.5 (Schlede, 1989). The largest 

volumes of limestone are located, however, in the eastern part of 

the country. Exceptions are the extensive and thick Mesozoic 

limestone and gypsum sequences in the Blue Nile River arka in 

Cend Ethiopia. 

Proterozoic limstoneldo~omite deposits in Western and 

Southwestern Ethiopia have considerable potential as they are 

located close to the acid soils. Dolomitic limestones and marbles 

helve been reported from many places in western Ethiopia, 

including Daletti, near Mendi. Liming material cm be found in 

Ethiopia within three major geological units: 

- In Proterozoic rocks, mainly as marble; 

- In Mesozoic sedimentary sequences, main1y as limestone, 

dolomite, and marl; 

- In Caenozoic sediments, as limestones, dolomites, and 

marls.

I 

156 Mineral Resources Pbtential of Ethiopia 

Proterozoic liming matelriala Roteromic marbles occur in 

northem Ethiopia (Tigray), in the west (Gojam, Wollega, Illubabor, 

Ma), southern (Orno, Sida.) and eastern (lharghe) parts of 

Ethiopia. A general observation is that these resources occur in 

areas where strong to moderately acid soils (pH< 5.5) sre 

dominant. 

Mesozoic liming materials, Mesozoic limestone, dolomitic and 

marl deposits in westem and rmrthern Ethiopia occur in Tigray, in 

the Danakil Alps and in the Blue Nile (Abay) valley. They also 

outcrop over large areas on the Somali Plateau. Smaller outcrops 

of Mesozoic liming materials occur in the central PIateau area near 

Ambo town, in the Didessa valley. Smaller deposit occurs in the 

Kella area south of Addis Ababa. The Jurassic Ando Group with 

sequences of limestone, dolomites and marls occur in the Blue Nile 

(Abay) valley and the Mekele (Tigray). In the Mekele area the 

Anterlo limestone is about 750 rn thick (Getaneh, 1985). In general, 

the Mesozoic limestone, dolomite and marl ~ESOW are located 

further away from m s with strong to moderate ?id soils 

I (pH

I 

.. ' 

- , 

. . -. .-..- - 

, , , ,,.-,A, 

. A Industrial Minemls 157 

named Madern Building Industry PK., lacated in Awash, which is 

engaged in processing a dolomitic marble' in order to manuf..~ 

a standardized filler mineral at the required micro sizes. At t$gJ 

moment this company is supplied with the dolomitic marble from* 

the Kenticha Precambrian racks. The application of gypsum as a 

soil amendment for ahline soils on S-deficient soils and for 

groundnut production should be agronumically t d . Gypsum 

deposits should also be tested on the acid soils of westem Ethiopia, 

especially in acid soils with high Al-toxicities. 

Local resources of agricultural limestones and dolomites, as 

well as gypsum, should be investigated for their potential to 

ameliorate acid and Al-toxic soils, As in many countries, these 

morns of 'aglime' and dolomite have largely been overlooked. 

Research should be carried 'out to determine cost-effective 

extraction and low-cust crushing and grinding technologies 

I followed by demonstration of the apnomic effectiveness of 

liming materials and gypsum on acid soils. Further exploration and 

' testing of their suitability and agronomic effectiveness are neded. 

In addition, it is important to demonstrate the benefits of using 

I local lirnestone/dolomite and gypsum to farmers.

I 

158 Mineral Remums Fbtential of Ethiopis 

I 

i 

t~gure ;?o A large out-crop of dolomrt~c marble wnnln grapnlte 

Kenticha, Adola 

. Eleinental sulfur can be found near hot springs and volcanic 

regions in m y parts of the world. Such volcanic deposits are 

currently exploited in Indonesia, Chile, and Japan (Noetstaller, 

1988). Significant desposits of elemental sulfur also exist in salt 

domes along the coast of the Gulf of Mexico, and in evaporites -in 

Eastern Europe and western Asia. The sulfur in these deposits is 

believed to come hm the action of anaerobic bacteria on sulfate 

eerals, especially gypsum. Such deposits are the basis for 

commercial production in the United States, Poland, Russia, 

Turkmmistan, and Ukraine (Noetstaller, 1988). 

Common naturally occurring sulfur compounds include the 

metal .sulfides, such as pyrite (iron sulfide), cinnabar (mercury 

sulfide), galena (lead sulvex sphalerite (zinc sulfide) and stibnite 

(antimony sulfide); and the rnd sulfates, such as gypsum 

cium sulfate), aiunite (potassium aluminium surfate), and barite

1 I 

Industrial Mjnorah '1 59 

(barium sulfate). Hydrogen sulfide is the gas respomible for the 

odor of rotten eggs. It accurs naturally in volcanic emissions, such 

as from hydrothemat vents, and from bacterial action ofl decaying 

sulfur-containing orgauic matter. 

Applications 

Sulfur has rnany industrial uses. Through its major derivative, 

sulfuric and (&SO4), sulfur mpks as one of the more important 

elements used as an industrial raw material. It is of prime 

impo&ce to every sector of the world's economies, Sulfuric acid 

I 

I 

production is the major end use for sulfur, and consumption of 

sulfuric acid has been regarded as olie of the best indices of a 

nation's industrial development. More sulfuric acid is produced in 

the United States every year than any other industrid chemical. 

Sulfur is dso used in batteries, detergents, the vulcanimtion of 

rubber, fungicides, and in the manufacture of phosphate fertilizers. 

Sulfiks are used to bleach paper and as a preservative in wine and 

dried hit. Because of its flammable nature, sulfur dm finds use in 

matches, gunpowder, and fireworks. Sodium or ammonium 

thiosulhte is used as photographic fixing agents (Noetstaller, 

I 1988). 

There are small and scattered occurrences of native sulfur in the 

sediments and associated volcanic activities of the Rift Valley and 

in Danakil Depression. All are solfhtara-type associated with 

fmambs and crater deposits. The Danakil Depression resource at 

Zariga, north of Dallol, and on-mlol hill are estimated at 0.36 Mt 

at a grade of 5&55% sulfur. Anothk resource west of Dallol, on 

the road to Musley and Chebret Ale-crater, was reported to contain 

0.2 and 7 million tons at a &e of I&20% and 900? sulphw 

' respectively (EGS, 1989). There are various sulfur deposits in the wfl 

D-l Depression and mud Dofan deposit in the central rift


are$ and most of them are of volcanic odgin formed by gasous or 

hmlic activity around volcanic crater and hot springs. 

Localities of sulfur occurrences: 

- Sulfur occurs in Zariga (20 km north of Dallol) on the road to 

Mersa Fatirna and in two other localities in Dallol area and 

Cheberet Ale deposit (spring deposit due association with a 

crater) is 60 km south east of Dallol; 

- Sub also occurs in the Dofan vobano in the central rift 

valley at (8021'27"N and 40' 07'09"E). It is fomed by 

continuous fumerolic activity having impregnated a limited 

amount of element. sulfur by sublimation within the porous 

pumice and scoria layers and dso along fmtwes; 

- Manda is also known for sulfur deposits which are still 

exmcted by l ad ppIe. 

In addition, &bent exploration activities by EGS, at DofaR west of 

Awash River, revealed a deposit of 2,900 tons with sulfur grade at 

626%. 

4.20 Pumicdscoria 

Pumice is a highly vesicular pyroclastic igneous rock of 

intermediate to siliceous magmas including rhyolite, trachyte and 

phonolite. Mice is usually light in colaw ranging from white, 

yellowish, grey, grey brown, and a dull red. Pumice has an average 

porosity of W/o. Pumice is formed as pyroclastic material is 

ejected into the air as a froth containing masses of gas bubbles or 

vessicles; the lava solidifies and the vessicles are contained in the 

rock. The basaltic version of pumice is horn as scoria and has 

m y differences due to mineralogy. 

Pumice is widely used to make lightweight concrete and as an 

abrasive, especially in polishes and cosmetics exfoliants. When 

used as an additive for cement, a hie-graid version of pumice


called p omb is mixed with lime to form a light-weight, smooth, 

plaster-like cbncrete. 

Pumice deposits in Ethiopia 

Large resources of volcanic scoria and pumice have accumulated 

within and along the margins of the rift valley. These resources can 

be used in soil moisture conservation techniques, called rock 

mulching. Experiences from other parts of the world, especially the 

Canary Islmdq have shown that rock mulch can considerably 

reduce evaporation from soil surfaces. 

Pumice occurs in several localities of the Rift Valley as 

recent shore sediment of lakes and also as older lacustrine 

sediments. Pumice =ewes are located near Nazareth railway 

station and in the Mojo stxea. Other deposits occur as shore 

sediments at Debrezeit, Langano, Awassa and other Rift Valley 

Lakes, Rock mulch field experiments using local scoria and 

pumice resources fiom near Naareth were carried out in the 

wework of the Ethiopia-Canada agrogeology project (Woldeab 

ei al., 1 994). The results of field experiments illustrated the effects 

of scoria and pumice mulches in the Rift Valley of Ethiopia. The 

application of 3 to 5 crn scoria or pumice mulch on top of the soil 

swfim resulted in effective soil moisture conservation, as well as 

grain yield increase of maize by as much as 4 he (Wold& et 

al., 1994). The main constraints to this system are availability of 

mulching materids in the close vicinity to soils with moisture 

stress, and economics. 

4.21 Natural zeolites 

Zeolites are the aluminosilicate members of the family of 

microporous solids known as "molecular sieves". Zeolites are 

widely used as ion-exchange beds in domestic and commercial 

water purification, softening, and other applications. In chemistry, 

zeolites are used to separate molecules (only molecules of certain

162 M i d Resources Potential of Ethiopia 

sizes and shapes can pass through), as traps for molecules so they 

can be andyzed. Zeolites have the potentid of providing precise 

and specific separation of gases including the removal of H2Q, 

C02 and SO2 from low-grade natud gas streams. Other 

separations include: noble gases, N2, freon and formaldehyde. 

However, at present, the true potential to improve the handling of 

such gases in this manner remains unkmwn. 

Currently, the world's annual production of natd zeolite 

is about 4 million tons. Of this quantity, 2.6 million tons' are 

shipped to Chinese markets to be used in the concrete industry. 

Eastem Eumpe, Western Europe, Australia, and Asia are world 

leaders in supplying the world% demand for natural zeolite, By 

comparison, only 57,400 mettic tons (wurce: U.S. Geological 

Survey, 2004) of zeolite (only 1% of tke world's cmmt 

production) is produced in North America+ 

Natural zeolites form where volcanic rocks and ash layers 

m t with alkaline groundwater. Zeolites also crystallized in postdepositional 

environments over periods ranging from thousands to 

millions of years in ~Ilow marine basins. Ndly occurring 

zeolites are rarely pure and are contaminated to varying degrees by 

other minerals, metals, quartz or other zeolites. For this m o , 

naturally occurring zeolites are excluded from many important 

commercial applications where uniformity and purity are essential. 

Natural eeolite deposits in Ethiopia 

Several million tonnes of high-grade zeolite deposits (mordenite 

and clinoptilolite) were discovered by geologists of the Ethi* 

Canada agrogology project in rift valley sediments nmr Nmth 

and Boru, west of N mth, Muger and Gondar (Fig. 37). Zeolites 

have high cation exchange capcities and, specifically, high 

ammonium selectivities. There we many applications of zeolites in 

agriculture and horticul~, among them are applications of 

zeolites in chicken houses that can reduce the losses of

ammonium-nitrogen by ion dchange and adsorption lht~ t?~ 

channels of zeolites, These ammonium-charged zeolites could be 

used as an effective slow-release of soil amendment The extent ~f 

the natural zeolites in the Rift VdIey should be surveyed, and the 

zeolites need to be characterized mineralogically and chemichlly. 

Pradcal. applications for the natural. or mdifid. zeolites of 

Ethiopia in aaiculture and horticulture have to be assessed, 

FIgm 37 Acfcuh zealits (mt~) crystal w 

4 

'4.22 Mineral waters 

Mineral water is water containing minerals or other dissolv 

1 substances that alter its taste or give it therapeutic value. Salts, 

1 

i 

sulficr compounds, and gases are among the substances chat can be 

dissolved in the water. Mineral water can often Ix effervescent. 

Muaal warn bc prepared em occur naturally.

I 

I Humasa, 

Traditionally mineral waters would be used or consumed at their 

source, often refeked to as taking the waters or taking the cure and 

such sites were referred to as spas, baths or wells. Spa would be 

P 

used whh the water was consumed and bathed in, bath when the 

water was not generally consumed and well when the water was 

not generally bathed in. Often an active tourist centre would grow 

up around a mineral water site (even in ancient times). Such tourist 

development resulted in spa towns and hydropathic hotels (often 

shortened to Hydros). In modern times, it is far more common for 

mineral waters to be bottled at source for distributed consumption. 

Mlneml watem deposits in Ethiopia 

More than 130 thermal springs are known in Ethiopia of which 

about 70 are situated within the Rift System (Nech Sar, Abaya, 

Matigola, Blate, Cherico Gidabo, Grabs Quhe, Wondo 

Genet, Kike, Dubicha, south lake Shda, east lake Shala, Tub 

Gudo island, Bole graben, Edo Laki, Oitu Bay, Alemtena and 

Koka, Gumare pool, Sodere, lake Beseh, Wasero, Bilen, lake 

Hertde, Erer Gota, Meleka, north Gewane, Issa graben, Wanuf, 

KiIelu, Danab (Maru), Teo, Gamma, Muluke, Chachetu, 

Allalobeda, Kio Derayta, Dobi, Seha, Mantebo, Uluye, Gugubdo, 

lake Afdm, Ain Allah, lake Bakilli, lake As'ale, Dalol, Black 

Mtn, Musley and the rest on the Plateau, mostly in the Lake Tana 

Basin (Getahun, 2002). 

4.23 Other metallic and industrial minerals 

A wide variety of other metallic and industrial minerds is known 

to occur in various geological environments (Table 2); among 

them mention can be made of mercury, wolframite, vanadium, tin, 

tungsten, asbestos, pozzolane, pyrite, and vermiculite. Most 

promising sites hosting rocks and industrial minerals are the


Moyale graphite deposit (0.46 Mt), the Garibaldi Pass (Nazareth) 

pozzoline deposit, the Kenticha area for high-quality quartz (0.26 

Mt) and the big fumaroles sulfur deposit of Chebret Ale (6.5 Mt of 

S) (EGS, 1989). Investigations have been made regarding several 

of these commodities, but little published information is available, 

and qmtity, quality and economic considerations have not been 

studied in any detail. 

Role of Iodustrlal Minerals in the National Economy 

Worldwide it is estimated that sand, gravel, limestone, clay, sulfur, 

salt, and phosphate make up 90% of the total tonnage of all 

industrial minerals and rocks produced and 60% of total value. The 

widespread use of industrial minerals and rocks is in large part due 

to two characteristics of these materials. Firstly, the use of a single 

mineral in one production process often involves the use of several 

others. For example, the production of glass from silica sands may 

require the use of soda ash, limestone, dolomite, feldspar, borax, 

1 gypsum and fluorspar. Secondly, a single mineral or rock may 

form the basis for a large number of industries. A very good 

example is limestone which may be used in the construction, 

metallurgical, agricultural, and chemical industries. Lime, a 

product derived from limestone, is itself a raw material used in the 

production and processing of a myriad of products such as glass, 

steel, chemicals, paper, sugar, paint, water and food. Other major 

industries like chemicals, fertilizers, ceramics, and metallurgy 

depend on industrial minerals and rocks as a source of raw 

materials. Above all, these minerals and rocks provide the raw 

materials for infrastructure development in which large volumes of 

sand, gravel, clay, crushed and dimension stone are consumed.

Chapter 5 

Construction materials and dimension stones 

+ 

Using stones as an ornamental material for beauty and durability in 

all kinds of construction dates back to the dawn of civilization 

Almost every variety of rock has been used as dimension stone, as 

the suitability of a particular stone for dimension stone is governed 

primarily by its physical properties m_d its specid appeal to 

humans. The ornamental dimension stone is becoming very 

popular for the basic reason that it renders a romantic beauty to the 

fascinating architects of modern buildings. 

Stone that is linished to specific dimension and shape is 

considered as dimension stone. Other stones, referred as building 

stones, me sold in either natural or broken sizes and shapes and are 

sorted into size ranges but not finished or dressed to specific 

n dimension. The term "dimension stone" is defined as naturally 

murring rock material cut, shaped or selected for use in blocks, I 

slabs, sheets or other construction units of specified shapes or sizes 

and used for external or interior parts of buildings, foundations, 

curving, paving, flogging, bridges, revetments, or other 

architectural or engineering purposes. The term is dso applied to 

quarry blocks from which piqep of fixed dimensions may be cut. 

Marble, granite, limesthe, md sandstone provided the bulk of 

dimension stone, although slate, diorite, basalt and diabase are 

included. 

The classification of dimension stone is not strictly adhered 

to sedimentary, igneous and metamorphic puping of geology, as 

the stone trade name under "granite" refers to all true granite and 

gabbro, norite, and syenite. Likewise all crystalline limestone, 

travertine, sandstone and serpentinite that are capable of taking a 

polish are grouped under marble in addition to the true marble. As 

the distribution of rocks is governed by geologic factors, the 

diverse geological environment of Ethiopia has ultimately formed

1 ' 

".:-' 168 :@inaal .Reso~r&:PotmtinI 6f Ethiopia 

cdidrless aTp P wry .pn. a of @oi+ 

whiih "is *-in ,a wide variq of idustries Finely pro 

pb6der is a con@pge.nt in paints, toothpaste; and p~astics; 

&n& can . also 

, - 

. be radw ugder high h d to cslciuni 

(a& kn'ovh as %&), which has many applications inc 

mg a primary compnqpt of most merits. 

Marbles are widespread in the bademat r&ks df Ethiopia, in 

particular the Pmterozoic calcmus schistg, Same of these have 

beem exploited by the cement industry and the Nafid Mhhg 

Company. The late Pmterozoi~ to early Pdaeomic marbles< pf the 

Tsalient and Tmbitn pups am known not to have complete 

mqsEallkWnmn .han$don of the parent limestone to 

die. PLU& rnriditjdm of -bib are very .ideal .for dimension 

stones and l$hey~w w&onlp~ found in northem -Ethiopia. These 

mcts +W 'biotb; ~ ~ s t iof c+ne s mi die, although 

ireftmdmmpsi~e hhk Jimstane, K e d l~imestone (800,m 

thic&),md &em ~li~estone ,(3QO n ck) ad commonly loccur in - 

Y 

r 

Ddjdepressj~n.~ , 1 , 

4 

. 

miation with intmbwls of slate, mhfble./and dolomite. In this 

combdon, ' bi ~~&ilihm. formatidn, 'the youngest of the 

, btmzoic mck, (1,S0,0 m. tk~k). MC, 2003) consists of 

- mish -to white. dolomite. This unit h dso found txpd in the 

r 8 

13. the- hi-ry, of conshyctiorxt in Ethiopiq marble is th 

most ension ion stone. For instame, some of the Addis 

, Abba's;~oldip high gtmey, building% e. g. the, :National Bank ,of 

' EtBioph.were buiIt'afmwb1e:fur inmd and extnal application. 

The highly exclusive and- luxurious, ,five star hotels, Sheraton 

Addis, has been the most modern and recently built commercial 

I 'building in Addis A W. Thia hotel is the fi& building to have 

I

1 74 Mineral Reswrces Potential of Ethiopia 

crystals larger than the groundmass forming a rock known as 

porphyry. Wtes can be pink to dark grey or even black, 

depending on their chemistry and mineralogy. Occurrence of 

granite is currently known only on earth where it forms a major 

part of continental crust. Granik occurs m relatively small, less 

than 100 km2 stock-like misses and as large batholiths often 

associated with orogeaic mountain ranges ar;d is frequently of 

great extent. Small dikes of granitic composition called aplites are 

associated with granite margins. In some locations very coarsegrained 

pegmatite masses occur with granite. 

mite has been intruded into the crust of the earth during 

all geologic periods; much of it is of Precambrian age. Granite is 

widely distributed throughout the continental crust of the earth and 

is the most abundant h e n t rock that underlies the relatively 

thin sedimentary veneer of the continents. Despite being fiairly 

common throughout the world, the areas with the most commercial 

W t e quarries are located in the Scandinavian Peninsula (mostly 

in Finland and Norway), Spain (mostly in the Gdicia ma), Brazil, 

India and several countries in the South end of the Afiican 

continent, namely Angola, Namibia, Zimbabwe and South Africa. 

Origin 

Granite is an igneous rock and is formed from magma. Granite 

magma has many potential origi*ns, but it must intrude other rocks. 

Most granite intrusions are emplaced at depth within the crust, 

usually greater than 1.5 km and up to 50 km depth within thick 

continental crust. The origin of granite is contentious and has led to 

varied schemes of classification. Classification schemes are 

regional. There is a French scheme, a Bnu scheme and an 

*? 

American scheme. This confusion arises kcause the classification 

schemes define granite by different means. Generally the 'alphabet- 

soup' classification is used hause it classifies based on genesis or 

origin of the magma.

w;i;y 

Gems~ones and Semi-precious Stones 187 

to the surface by the basaltic magmas. Most of the world's 

emeralds are mined from low-grade carbonaceous schists in 

Colombia, South America. In Australia, emeralds occur within 

biqtite schists found in Western Australia, and within pegmatites in 

the New England region of New South Wales. Other gemstones 

which occur in metamorphic rocks include ioUte (the gemquality 

lilac-purple variety of cordierite), timite and kyanite. Jade is a 

term given to tough compact aggregates of two minerals, i.e. 

jadeite (a pyroxene) and nephrite (a term given to a group of 

amphibole minerals, not a minerd). 

Sedimentary deposit 

By far the most valuable gemstone formed in sedimentary 

envirqnments is precious opal. The largest deposits of this occur 

throughout central Australia in the far western New South Wales; 

muth-west Queensland; and central to northern South Australia in 

what is known as the Great Artesian Basin. Most of these opal 

deposits occur in fine-grained rocks of Cretaceous age. 

Placer deposit 

Because of their toughness and resistance to weatherin 

erosion, gemstones arerelativeli abundant in some placer deposits. 

Most of the sapphires from eastern Australia occur in placer t 

deposits where they have become concentrated by alluvial 

processes. Other important gemstones which commonly awur in 

placer-type deposits include diamond, zircon, topaz, ruby, garnet, 

agates and petrified wood. 

Gemstone deposits Io Ethiopia 

It is known that Ethiopia is endowed with suitable geol 

m 

environments to host all varities of gemstone, although not yet -., , 

been well investigated in detail. Nevertheless, miner s o z- 

I

188 Mineral Resources Potentid of Ethiopia 

gemdtones (e.g. beryl, aquamarine, tourmaline, pet, spinel, 

top~z, chalcedony and agate, jasper, petrified wood, chrysoprase) 

are reported to occur in Sidamo (Kenticha, Kibre Mengist area), 

Harm (Babile, Jijiga: amethyst, garnet), and Tigray (Axum and 

Adwa area: amethyst, agate, chalcedony). Primary occurrences are 

related to pegmatite-granite rocks; the gravels of some of the major 

rivers of Ethiopia host some secondary alluvial occurrences. 

Besides, there are plentiful indications suggesting the presence of a 

variety of gemstones in Ethiopia, including ruby (Kibre Mengist), 

sapphire @ills area), emerald (Cheri, Fularia, Moyale), and 

diamond (Turmi, Moyale). Gemstone is, therefore, regarded as one 

of the rich mineral resources of the country, which deserves proper 

investigation. 

Artisanal and small-scale miners produced a variety of 

gemstones. Opal was found at Mezezo in Amhara Regional State; 

garnet, at Harshitmi; sapphire, at Bonga; aquamarine, at Chembi, 

Kenticha, and Kilkile; emerald, at Chembi; and peridot, at 

Chewbet, Gofa Gedo, Mega, Megado, and Tbsy. Other gemstones 

produd included amazonite, amethyst, quartz, and tourmaline. In 

fiscal year 2003-04, -the production of opal increased to 370 kg 

from 187 kg in fiscal year 2002-03; md garnet, to 1 1 kg from 6 kg. 

Presently there is a very widespread illegal transactions of 

gemstones largely smuggled out of Ethiogia. According to the 

Mineral Operation Department, the gemstones involved in illegal 

transactions include opal, bwyl, corunddum (ruby and sapphire), 

garnet, and peridot. It is also lemt that many gemstone bearers 

were not willing to locate where the gem came from. Therefore, 

this seems so crucial considering the urgent -need required to 

reduce illegal trading and smuggling out unprocessed gemstones,

6.1 Corundum (ruby and sapphire) 

Sapphire is the single-crystal form of aluminium oxide (A1203), a 

mineral known as corundum. It can be found naturally as 

gemstones or manufactured in large crystal bodes for a variety of 

applications. The corundum group consists of pure aluminium 

oxide. Trace amounts of other elements such as iron and chromium 

give sapphires their blue, red, yellow, pink, purple, orange or 

greenish color. Sapphire includes any gemstone quality varieties of 

the minerd corundum including the red variety, which is also 

known as ruby. Ruby is a red gemstone, a variety of the mined 

conmdum (aluminium oxide). The color is caused mainly by 

chromium. Its name comes hm ruber, Latin for red. Natural 

rubies are exceptionail y rare, but synthetic rubies (sometimes 

called created ruby) can be manufactured fairly cheaply. Other 

varieties of gemquality corundum are called sapphires. It is 

considered one of the four precious gems together with sapphire, 

the emerald and the diamond. 

Rubies are mined in Africa, Asia, Australia, and Greenland. 

They are most often found in Myanmar (Burma), Sri Lads 

Kenya. Madagascar, and Thailalld, but they have also been found 

in the U.S. states of Montana, North Carolina and South Carolina, 

The Mogok Valley in Myanmar has produced some of the finest 

rubies, but in recent years very few good rubies have been found 

there. In central Myanmar the area of Mong Hsu also produces 

rubies. The latest ruby deposit to Lx found in Myailmar is situated 

in Narn Ya. In 2002 rubies were found in the Waseges River area 

of Kenya. Rubies are being mined at Audilamena in northeastern 

Madagascar. Sometimes spinels are found dong with rubies in the 

same rocks and are mistaken for rubies. However, fine red spinels 

may approach the average ruby in value. Rubies have a hardness of 

9.0 on the Mohs scale of minerd hardness. Among the natural 

gems oqly diamond is harder.

- - 

.;>*F,- 

190 MInehl Resourns Potential of Ethlopi 

Ruby and sapphi w occurrencess in Ethiopia 

' 

Ruby gem is known to occur in southern Ethiopia (Kibre Mengist, 

and Dilla ldity) (Fig, 39, 40). The occurrences are associated 

with marble, gneiss and schists in the basement rock. Sapphire 

gems are reported to occur in Dilla area associated with volcanic 

rocks (bmlts). There is a great illegal market of ruby and sapphire 

gem in the country. Therefore, systematic exploration is required 

to assess the ruby and sapphire potential of the region. 

6.2 Opal 

The mineraloid opal is amorphous SiOz*nH20; hydrated silicon 

dioxide, the water content sometimes being as high as 20%. On the 

basis of the interplay of colour, opal ranges from colorless through 

white, milky blue, grey, red, yellow, green, brown' and black. The 

high vdk of precious opal is adversely &ected such. that it 

becomes lower when the contrast between the iridescent patches 

and the background colour is less pronounced. It has also lower 

value if the colour patches are less clearly defined, Opal is a 

mikraloid gel which is deposited at relatively low temperature. 

Opal is normally found in association with effusive magmatic rock 

deposited in cracks and cavities by aqueous fluid at low 

temperature. It may also be found in siliceous sandstone where 

hydrous silica has been precipitated perhaps due to strong 

alteration of feldspar by percolating water; and is most commonly 

found with limonite, sandstone, rhyolite, and halt. 

Opal deposits in Ethiopia 

Recently, opal was discovd at Yita ridge in the 'b enz Gishe 

district of Shewa province. The opal site is located about 140 km 

north-west of Addis Ababa The opal-behg rock is a nodular 

rhyolite which is ~iocene in age. This opal occm within the 

hyolitic rock overlain by thin ~orltinwus bands of 3 to 30 m thick 

L.

I 

1 

b 

Gemstones and Semi-precious Stones 191 

pitchstone (vitric tuff) of the Algae Formation. The territory where 

opal is found is quite vast, The concession areas cmot be kept 

under permanent surveillance. The opal is found as spherical or 

elliptical nodule with the gem opal resting inside, It is possible to 

find as many as eight nodule of opal within one square meter. A 

slowly cooled siliceous fluiaava upon differentiation when 

extruded the thin continuous rhyolitic horizon. The gem variety 

opal accounts for the formation of a densely scattered 

ellipticdsphere nodules. The gem field has been estimated to 

extend over an area of at least 7 x 7 km. The opal nodules average 

about 10 cm in diameter. Rock with opal nodules, particularly 

visible on the collapsed block, height of the level, 4m. 

Recently, an opal nodule weighing 4-5 kg has been found 

by local people (Fig. 41). The opal from northern Shewa shows the 

internal interplay of colours, xeGealing various base colours; clear, 

translucent white lavender, red or anger yellow-green and blue 

- wlours (Fig. 42, '43). Such quality of precious opal is exceeded 

only by the four principal and highly priced gemstones (diamond, 

emerald, ruby and sapphire). Contrary to Australian opals, the red 

ones are 'the most common and the blue ones the rarest. The highland 

inhabitants collect the nodules, which are for sale in the 

capital city later on, It is in the nature of things; but it is forbidden 

to non-natives. There are seven concessions, but only three of them 

are king exploited. The precious opal is currently mined by a 

private company in small-scale, at Mam in northern Shew 

Amham National Regional State. The precious opal mined in north 

Shewa is exported largely semi-processed nodules. However, it is 

recommended that precious opal be exported being cut, shaped wnd 

finished here within the country. Other occurrences of precious 

opal are reported in Warder, Ogaden, and Dire Dawa, and Me; 

thus it is believed to be available in many parts of tbe country.


63 Beryl 

The mineral beryl is a beryllium aluminium cyclosilicate with the 

chemical formula Be3Al2(SiO3b. Varieties of beryl have been 

.;considered gemstones since prehistoric times. Green beryl is called 

emerald, red beryl is bixbite or red emeraid or scarlet emerald; blue 

r-Beryl is aquamarine, pink bryl is rnorgmite, white beryl is 

goshenite, and a clear bright yellow beryl is called golden beryl. 

Other shades such as yellow-green for heliodos and honey yellow 

are common. Beryl is found most commonly in granitic 

pegmatites, but also occurs in mica schists. Massive beryl is a 

primary ore of the metal beryllium. 

Beryl occurrenaes in Ethiopia 

Beryl is reported to occur in Chembi village, located 35 km north 

of Kibre Mengist, Southern Ethiopia The area is underlain by 

' various gneisses, meta-sediments and intrusive. The intrusive rocks 

are represented by ultrabasic rocks, granite and pegmatites and are 

exposed along the Genale River and Ababa vaIIey. The pegmatites 

are 1-2 m thick and 200 m long. The granites and pepatites are 

course and often host e nite and substantial amount of garnets, 

spodurnene, green spinel, apatite, malachite and beryl. Gem quality 

of greenish to bluish has been identified in this locality (Fig. 44, 

45). In the pegmatite, a beryl cr&al as large as 4 cm long has been 

found. Aquamarine and white beryl, emerald, ammonite, topaz are 

found in Kenticha and are associated with pegmatites. 

6.4 Olivine (peridot) 

Peridot is the gem quality variety of forsterite olivine. The 

chemical composition of peridot is (Mg, Fe)2Si04. Peridot is 

found in Arizona, Hawaii, Nevada, and New Mexico, in the US, 

and in Australia, Brazil, China, Kenya, Mexico, Myanmar

Gemstones and Semi-~wious Stones 193 

@ma), Norway, Pakistan, South Africa, Sri Lanka, and 

Tanzania. 

Olivine deposits in Ethiopia 

The precious olivine, peridot, occurs in Mega, 720 km south of 

Addis Ababa. There are also a number of localities, nameiy Gofa, 

Gofa Gedo. Tassy, Megado and Chewbet, that bear the gem quality 

olivine (peridot) (Fig. 48). All the localities lie within 30 km radius 

from Mega town and are associated with thick basaltic flows 

characterized by poor-phyritic olivine-bearing basalt near volcanic 

cone. Potential areas of peridot bve been delineated by EMRDC at 

the localities of Bulgendo and Alabora enclosed with in dark grey 

olivine basalt. It is also interesting to note that the gem quaiity 

olivine occurs within large xenoliths of dunite and peridotite 

engulfed within the young yet olivine bearing trachitic basalt 

indicating the depth of formation and transportation which may be 

good indication for others such as diamond. A regional geologicd 

mapping and detail mapping in specific localities had been 

conducted in the area by EMRDC resulting in delineating potential 

areas for peridot at Bulgendo and Alabora. In Bulgendo the gem 

quality is enclosed within the dark grey olivine basalt, covering an 

area of 22 km2. The gem quality of the peridot in these localities 

are reported to be rated of high and medium with estimated reserve 

of 2457 kg (EMRDC, 1985). 

Six wmmon varieties of garnet are recognized based on their 

chemical composition. They are .pyrope, dmandine or arbuncle, 

spessartite, giossularite (varieties of which ate hessonites or 

cinnamon-stone and tsavorite), ,uvarovite and andradite, Gmets 

are most commonly red in color but can Be found in a variety of 

colors, including purple, red, orange, yellow, green, brown, black,

194 Mineral Resources htential of Ethimia 

or colourless. Garnets are very abundant in the lower crust and 

mantie and thus play an important role in geochemical 

understanding of the Earth. The garnet is the birthstone for 

January. It is a symbol of faith and trust and when given as a gift is 

a tolken of devotion and loyalty. 

Applications 

Pure crystals of garnet are used as gemstones. Garnet sand is a 

good abrasive and a common replacement for silica sand in sand 

blasting. Mixed with very high pressure water, garnet is used to cut 

steel and other materials in water jets. Pyrope varieties are used as 

kimberlite indicator minerals in diamond prospecting. 

Garnet occurrence3 in Ethiopia 

Deep red garnet (almandine) crystal is reported to occur in 

Harshitmi locality, about 20 krn east of Moyde town. The garnets 

are rlssociatd with high grade metamorphic rocks (quartzmuscovite 

schist). The crystals are up to 4 cm long (Fig. 49). Baya 

Corelli and Bow in southern Ethiopia are other localities where 

red garnet accurrence is reported. In these localities, dmandine 

garnet is present in the residual deposit derived from the 

underlying gn iss and schist. Garnet (almandine) occurs in large 

\ 

quantities along the mica of the Carrara deposit to the east of the 

Harar-Jijiga road where small-scale operation by local inhabitants 

takes place. Baya Corelli in southern Ethiopia, is another locality 

where red garnet occurrence is reported. In this locality, almandine 

garnet is present in the residual deposit derived, from the 

underlying gneiss and schist. Similarly in Bonga deep red 

porphyroblatic garnet as large as 5 crn in diameter have been found 

within gmet-silIimanite gneiss. Garnet is made up 4040% of the 

rock mass and is considered as an important deposit for abrasive 

manufacturing. Other gamer occurrences are reported to occur in

Gemstones and hi-&ws Stones 195 

Babile (Harm) and Adols area. An occurrence of this gem quality 

gamet is well known by the local people in southem Ethiopia, 

6.6 Quartz 

The precious quartz crystals reveal various mlours. Amethyst, the 

clear purple or bluish violet variety, and rose q w rose-red or 

pink are found in Ethiopia (Fig. SO, 5 1, 52, 53). The colorless 

quartz, as o h is the case, is popularly known as rock crystal and 

used for mdhg cheap jewelry. It is also utilized to manuoptical 

glass. Although the source is not yet known, rose and >tke 

colokless quartz are illegally sold in the black 'market in Addis 

Ababrr. 

6.7 Diamond 

The occ~ces of diamond have been reported in Tmmi, Moyale 

area of the southern Ethiopia. The quality ad quantity is yet 

unknown, There is a great illegal market of diamond in the area by 

I d people. Therefore, systematic exploration is required to 

assess the diamond potential of the ~gion.

196 Mineral Podcntlal of Ethiopia

1 Gemstones and Semi-prmious Stones 197

198 Mined Remums Patential of Bthiopia

7.1 Fossil fuels 

Chapter 7 

Energy Resources 

There are three major forms of fossil fuels; coal, oil and natural 

gas. All three were formed many hundreds of millions of years ago 

before the time of the dinosaurs -hence the name fossii fuels. The 

age they were formed is called the Carboniferous Period. It was 

part of the Pdeomic Era "Carboniferous" gets its name from 

carbon, the basic element in coal and other fossil fuels. 

The Carboniferous Period occurred from about 360 to 286 

million years ago. In that period, the land was coveflwith 

. swamps filled with huge trees, ferns and other large leafy plants. - 

The water and seas were filled with algae -the green stuff that 

forms on a stagnant pool of water. An algae is actually millions of 

very small plants. 

Some deposits of coal can be found during the time of the 

dinosaurs. For example, thin carbon layers can be found during the 

late Cretaceous Period (65 million years ago) -the time of 

Tyrannosaurus Rex. But the main deposits of fossil fuels are from 

the Carboniferous Period (MaCabe, 199 1). As the trees and plants 

died, they sank to the bottom of the swamps of oceans. They 

formed layers of a spongy material called peat. Over many 

hundreds of years, the peat was covered by sand and clay and other 

minerals, which 'turned into a type of rock called sedimentary. 

More and more rock piled on top of more rock, and it weighed 

more and more. It began to press down on the peat. The peat was 

squeezed and squeezed until the water came out of it and it 

e*ntually, over millions of years mimed into coal,. oil or 

petroleum, and natural gas.


7.1.1 Coal 

Coal is a naturally occurring combustible material consisting 

primarily of the element carbn, but with Iow percentages of solid, 

liquid, and gaseous hydrocarbs)ns and other materials, such as 

compounds of nitrogen and sulfur. Coal is usually classified into 

the sub-groups known as anthracite, bituminous, lignite, and peat. 

The physical, chemical, and other properties of coal vary 

considembly from sample to sample. 

Coal forms primarily from ancient plant material that 

accumulated in surface environments where the complete dscay of 

orgaaic matter was prevented, For example, a plant that died in a 

swampy area would quickly be covered with water, silt, sand, and 

other sediments. These materials prevented the plant debris from 

reacting with oxygen and decomposing to carbon dioxide and 

water, as would occur under normal circumstances. Instead, 

v b i c bacteria (bacteria that do not require oxygen to live) 

' . attacked the plant debris and converted it to simpler forms: 

primarily pure carbon and simple compounds 

hydrogen (hydroarbom). Because of the way it 

(along with petroleum and natural gas) is often 

fossil fkl. The initial stage of the decay of a 

woody material known as paf. In some parts of the world, peat is 

still co1Iected from boggy areas and used as a k l. It is not a good 

fuel, however, as it burns poorly and with a great deal of smoke. 

If peat is allowed to remain in the ground for long periods 

of time, it eventually becomes compacted as layers of sediment, as 

overburden, collect above it. The additional pressure and heat of 

the overburden gradually converts peat into mother form of coal 

known as lignite or brown coal. Continued compaction by 

overburden then converts lignite into bituminous (or soft) coal and 

finally anthracite (or hard) coal. Coal has been formed many times 

in the past, but most abundantly during the Carboniferous Age 

(hut 300 million years ago) and again during the Upper

Energy Kesoams 20 1 

CreWus Age (about 100 million years ago). Today, coal formed 

by these processes is often found in Iayers between layers of 

sedimentary rock. In some cases, the cod layers may lie at or very 

near the earth's surface. In other cases, they may be buried 

thousands pf feet ,of meters under ground. Cod seans range from 

no more than 3-1 97 A ( 140 m) or more in thickness. The location 

and confqpation of a coal seam determines the methud by which 

the coal will be mined. 

Cod is regarded as a non-renewable resource, meaning that 

it was fomed at times during the Earth's history, but significant 

amounts are no longer forming. Large supplies of coal are known 

to exist (proven reserves) or thought to be available (estimated 

resources) in North America, the fonner Soviet Union, and parts of 

Asia, especially China and India. According to the most recent data 

available, Chim produces the Cargest amount of coal each year, 

t about 22% of the world's total, with the United States 19%, the 

brmer members of the Soviet Union 16%, Germany 10% and 

' PoM 5% following. Chins is also thought to have the world's 

largest estimated resources of coal, as mu& as 46% of dil that 

exists. In the United States, the Iargest coal-producing states are 

Montana, North Dakota, Wyoming, Alaska, Tllinois, and Colorado 

(MaCabe, 1491). 

Cod is still used in industries such as paper production, 

cement and ceramic manuf&ture, iron and steel production, and 

chemical manuf~chm for heating and for steam generation, 

I 

Another use for coal is in the manufacture of coke. Coke is newly 

pure &n produced when soft coal is heated in the absence of 

air. A number of processes have been developed by which solid 

coal can be converted to a liquid or gaseous form for use ws a fie!. 

Conversion has a number of advantages. In a liquid or gaseous 

form, the fuel may be mier to transport, and the conversion 

process removes a number of impurities from the original cod

202 Mineral Resources Potmtial of Ethiogia 

(such as sulfur) that have environmental disadvantages. One of the 

conversion methods' is known as gasification. In gasification, 

crushed coal is reacted with steam and either air or pure oxygen. 

The coal is converted into a complex mixture of gaseous 

hydrocarbons with heat values ranging fiom 100 Btu to 1,000 Btu. 

One suggestion has been to construct gasification systems within a 

coal mine, making it much easier to remove the coal (in a gaseous 

I form) hm its origid seam. 

In the process of liquefaction, solid coal is converted to a 

petroleum-like liquid that can be used as a fuel for motor vehicles 

and other applications. On the one hand, both liquefaction and 

gasification are attractive technologies in the United States because 

of our very large coal resousccs. On the other hd, the wide 

availability of raw cod means that rmew technologies have been 

unable to compete ecunomically with the mtud product. During 

the last century, coal oil and coal gas were important sources of 

fuel for heating and lighting homes. However, with the advent of 

natural gas, coal distillates quickly became unppula~, &since they 

were somewhat smoky and foul-smelling. 

Types of coal 

As geological processes apply pressure to peai over time, it is 

transformed successively into: 

- Lignite also referred to as brawn coal, is the lowest rank of 

coal and used almost exclusively as fuel for stearn-electric 

power generation, Jet is a compact form of lignite that is 

sometimes polished and has been used as an ornamental 

stone since the Iron Age; 

- Sub-bituminous cod whose properties range fiom those of 

lignite to those of bituminous coal and are used primarily as 

fuel for stearn-electric power generation; 

- Bituminous coal, a dense coal, usually black, sometimes 

dark brown, often with well-defined bands of bright and

, m 

Enwgy Resources 203 

dull material; used primarily as fuel in steam-electric power 

generation, with substhial quantities also used for heat and 

power applicitions in manufacturing and to make coke; 

Anthracite, the highest rank, used primarily for residential 

and commercial space heating. 

Major coal producing regions 

China is the biggest producer of cod i~ &e world, while the United 

States and Russia contain the world's largest coal reserves. Europe 

Coal fields in South Wa(es, Yorkshire, other parts of the United 

Kingdom and Australia used to be major mining areas. .,. -',t ?. 

?.

' ! 

I 

I 

: I' 

I I - , 

' 


more energy-efficient way of using coal far eldcity production 

would be via solid-oxide fuel cells or molten-carbonate fuel cells 

(or any oxygen ion tramport based fuel cells that do not 

discriminate between fuels, as long as they consume oxygen), 

which' would be able to get 60%-85% combined efficiency (ditect 

electricity + waste heat steam turbine), compared to 3540% 

normally obtained with steam-ody turbines. 

Coal degasits in Ethiopia 

Geological Mng of coal dccumnc~~ of Ethiopia 

The coal occurrence of Ethiopia has been studied by several 

geologists and a number of reviiws, classifications and summaries 

have been published (Jelenc, 1966, Getaneh, 1985, Getaneh and 

Ssxena, 1984, Wolela, 1991,1995 and others). Most of the Ethiopian 

coals fall in the category of lignite. he& coal seams are f& 

associated and interbedded with the Cenozoic volcanics of the 

Northern Ethiopian F lateau. Some are associated with sediments that 

occur between the Mesozoic continental clastics and the Cenozoic 

volcanics, or sandwiched between the Precambrian hasement rocks 

and the Cenozoic volcanics (Getaneh, 1985, Getaneh and &err, 

1984). The lignite seams differ greatly both in their vertical 

thickness and lateral extent, and- the nature of their occurrence. 

Whereas some of them have relatively good lateral extension, the 

eeds about 1.4 m, though some may 

locally attain greater thicknesses. Table 10 lists the major lignite 

seams and the areas where they are found. According to Getaneh, 

199 1, depending upon their geological setting, the lignite deposits 

of Ethiopia can be broadly grouped into the following types: 

. 1. Inter-Trappean Lignite (Chilga Type); 

2. Infka-Trappem lignite (Arjo type); 

I, . . + 

--I 

4. I 

i' 

.

P 

. , 

Ug&e (CbilgiType) 

hrw mrces 20s 

$ @::of iig&'te occmnce, of which Chilga is the best 

example,, is found as .fluvatile andlor lamtrine intercalations 

within the volcilllios (Tmp Series) of Northem Ethiopian 

Plateau Lignite seams of Delbi: Moye, Meteso, Lalo-Sapo, Debre 

~ i ~ o~hida, s , Beressa, Mush Vdley, Soyoma, Wda, Chida 

Ankober, Sululta, Kindo, Wuchalle, kie, Dills, Jiren, dl belong 

to this group and occur under similar geological settings to those st 

Chilga. The lignite bearing are characterized by the presence 

of vol~clasts irregularly alternating with wyhg thickness of 

carbonaceous shale's with thin lignite seams, and qresent 

deposition during the periods of quiescence in between the 

volcanic eruptions. 

d 

G-eneraW stratigraphy of the Inter-Trappean type lignite 

Cen'bmic-volcanic rocks' with intercalations of continental 

volcaniclasts and shales with lignite seams 

. I . 

Mesozoiic - contitid and marine sedimentary mks 

, . 

Thea deposits, as the name makes clear, always occur below the 

Cenozoic volcolnics (Tmp Series), between the Mesozoic 

continental clastia and volmics, generally intermed with 

sedimentary rocks. Such deposits are few compared with Inter- 

Trajpan type. Examples of this type of occurrence include Arjo, 

Diddessa and Hun& Blesuma.

206 Mineral Resources Potential of Wliopia 

Generalized stratigraphy of the Infra-Trappean type lignite 

Cenozoic-volcanic rocks 

Shales with lignite seams 

Mesozoic - continental clastic sedimentary rocks 

-. ' . " , 

-. .' -. . +'.! ;:d&-; 

Nejo type lignite 

oj.:*- .&S 

,. These are found to occur between the Precambrian rocks and the 

Cenozoic vulcanik's (Trap Series). Some of them are not only 

covered by the vulcanite'si but also occur interbedded with them. 

Generalized stratigraphy of the Nejo type lignite 

Interbedded shales, mwls, sands and conglome 

with lignite seams 

Precambrian - basement mks

General characteristics of the coal deposits in Eth- 

Energy Resources 207 

Coal in general are assessed and classified on the basis of the 

amount of fixed carbon, percentage of volatile matter, ash content 

and calorific value. With favorable burial conditions (i.e. long 

periods of accumulation of vegetation, thick sediment cover, depth 

of burial, etc.) the deposits mature and there is a gradual increase 

in the fixed carbon content and other properties. Most of the 

Ethiopian coal, irrespective of their stratigraphic position and 

occurrence, fhll in the category of lignite that have been deposited 

under conditions lacking all these favorable factors and are, 

therefore, chmcbrkd by comp&atively low maturity and 

evolution (Getaneh, 1985, Wolela, 1991, 1995). Generally, they 

are thin bedded, less mature and with quite high mineral content. 

Consequently, most of the coal in general consists mainly of lignite 

that is of high ash content (2.4% to 65%), which fulfil the 

categories of soft coal, low fixed carbon (20% to 60.2%), low 

calorific values (range from 900 to 6,900 callkg) and average 

moisture and volatile content (fall under the categories of lignite to 

I medium-high volatile bituminous coal). However, there are coal 

seems having low ash contents and high calorific values (heating 

value) in the acceptable range for utilization in the energy sector. 

Since there are lignite with high calorific values (up to 6,400 

calkg) and low ash contents (e.g. as little as 1%) these could be 

blended with low calorific value and high ash-content lignite's to 

reach an optimum acceptable minimum (Getmeh and Saxena, 

1984). All these calls for a reassessment and =valuation of 

important lignite occurrences and W e d study of their economic 

I 

i 

I 

feasibility.

I 


Coal distribution in Ethiopia 

The following are descriptions of some of the better known 

deposits, some of which have received more attention in recent 

years. 

Yayu coal deposit (Illubabur) 

The Yayu area is located (8" 15'-8" 30'N and 35" 42L-36" 05' E). 

564 km from Addis Ababa along the Jima-Bedele-Gambella, or 

500 km along Nekemt-Bedele-GambeUa road. The sequence of 

coal and oil shale-bearing clastics is exposed around-Yap area in 

the eastern part of Geba River within the Geba Basin. Middle 

Oligocene to Early Miocene sediments are laying on a 

metamorphic basement floor with rernnants of older Tertiary 

basalts. The lithology of the succession comprises:' conglomerate, 

sandstone, siltstone, mudstone, oil shale, cod and tuff. The 

thickness of the coal seams ranges from 0.1 to 4 m. chemically; 

they are of high ash and medium sulfur content. 

Mush Valley coal depit 

Carbonaceous lignite deposit of the Mush Valley is situated 40 km 

from Debre Berhan in the direction of Dessie falling between the 

coordinates (9'45' 9" N and 3Y 40' 7" E). The lignite bearing 

sedimentary succession of Mush Valley area lie upon the Mio- 

Pliocene volcanic rocks of rhyolite composition. The Inter- 

Trappean sedimentary formatipn consists of an association of 

sandstones, sil tstones and shale's irreguIar1 y alternating with 

carbonaceous shale strata showing thin lignite seams. According to 

Getaneh, 1985, these rocks are as thick as 384 m, and are overlain 

by 134 m of tuff that occasionally interbedded with basalt and 

palaeosoils. Two coal bearing formations exposed at the banks of 

the Mush Valley (Babu and Getaneh, 1984) estimated the overall 

thickness of the two seams to be 1 m covering an area of 200,000 

sq m. This volcano-clastic sedimentary rocks crop out in the 

valleys of Mush River and its tributaries.

I 

I 

I 

t 

! 

a 

Five principal tmigenous rock types occur within the 

sections; sands and sandstones (20%), conglomerati~ siltstones 

(BOO! of the total sequ-) and gravely silt (9%), shale and' 

mudstones 66%) d carbonaceous shale and shale (5%). From the. 

natw and mode of murrence, the coal bearing stmta seems td be 

of fluvide origin deposited on the basalt substratum (Jelenc,, 

1966; Getmbh, 1'985; Wolela, 1991, 1995). Petrographical and 

chemical studies conducted by Babu eb al., 1980, revealed that the 

coal in Mush Valley has high moisture (19.3-2 1.34%) and ash 

content (52.1-54.2 % in hsh and 22.2% in dry), low carbon 

content (1.343.09 in fresh and 38,53 in dry) and low calorific 

value (3,82Q-4,020 cdkg in fresh and 4,552 W g in dry). 

Cbilga cod depodt (Gondrmr) 

The Chilga coal deposit is by f& the best known lignite deposit in 

Ethiopia It is situated northwest of Lake Tam (7'1 0'-T15'N and 

36O45'-36"55'E); not very fm from the capital of Gondar, and has 

' drawn artention since 1 93 0s. A total of 98 sq km was gedogically 

mapped by Heeman Wolfgang, Minye Behu and ~~leia in 1988. 

The area consists of Trap volcmics and sedimentmy rocks. The 

sedimentary sequence lies on a basaltic substratm which is 

Oligocene in age. The fluvial-lacustine coal bearing is mainly 

composled qf terrigenous clasts of (argillaceous and maceous 

maWs), orgamgenic deposits of cod ad mbmgillites. The 

thickness of the coal seams mge between 0.5-2.5 m. 

Delbi maat deposit (Ulubab~r) 

The Inter-Trappean fluvial-hdne coal and oil W e bearing 

sediment of Delbi is situated within the geogqhic coordinates 7' 

21 '-7" 24'N and 36" 5'-36" 53'E. Delbi is located 390 km southwest 

of Addis Abbq and 50 km south of Jimma. The Delbi cod 

and shale occurrence is one of the best studied coal deposit in 

Ethiopia using bore holes by Water well drilling project, 1983; 

Woleh er a]., 1991; Wolela et al., 1995; and others. The a m 

. . 

- 

- 4


consists of two major rock type!: Trap volcanies euid sedimentary 

rocks. The fluvid-lacustrine Delbi cod and oil shale-bring. 

formation is composed of mudstone, ~ ~ r ~ clay, o silt, u clay, s 

sand, sandstone, coal, organic shale and pyroclastic sediments. The 

thickness of the coal seam ranges 0.5-2.2 m. Petrographical and 

chemical studies conducted by the above authors revealed that the 

coal in Delbi has low moisture content (3.98-10.4%) and ash 

content 12.1-54.2 %) in fresh and 22.2% in dry), low carbon 

content (1,343.09 in fresh and 38.53 in dry) and low calorific 

value (4,000-5,000 cal/kg in fresh and 4,552 callkg in dry) 

(Wolela, 1 99 1 ). 

- 

Maye cod deposit (Illubabur) 

The Inter-Tappean continental fluvial-lacustrine sedimentary 

sequence of Moye is situated within the geographic coordinates 7" 1 

19'45" - 7' 24'7" N and 36' 48'21 " - 36" 5 1' E. It is located 59 

km southwest of Jimma and 14 km west of Delbi. Moye is one of 

the best studied coal deposit in Ethiopia by Wolela et a/., 1987; F;'7 

Assefa Aklilu et ul., 1987; ~inyk et al., 1988; Korean lignite 

exploration group, 1988. The area consists of volcanic kd I 

sedimentary rocks. The sediments are composed of mudstone, 

graded sandstone, sand y-bmcias conglomemte, carbonaceous 

4 

clay, coal and oi! shale. The volcanic rocks consist of basalt, tuff, 

pyroclastics and tuff breccias. The coal seams at Moye are grouped 

under humic coal (lignite-sub bituminous). 

Nejo-Meckeke coal deposit (Wollep) 

The fluvid-lacustrine lignite deposit of Nejo is located 9" 27'-9" 

33'N and 39" 19'-35" 29'E, 190 km west of the town of Nekemte. 

The area consists of three major lithological units: Precambrian :.- 

i ; c . 

c'-.*, 5 .. 

basement, pre-basaltic sediment and Trap volcanics. The basement $ :,: i, ' 

consists of schist, phyllite, and metasediment, metavolcanic and . 13 

dioritic intrusion. The pre-basaltic sediment overlies the basement $ : 

- and cupped by trap vdcanite's. The sedimentary sequence 

6'4 

:: , 

, x m , . 

*,*.. 

&:,: 

" .

Enagy Resou- 2 1 1 

commenced with quartz conglomerate which fines to silty clay and 

changed to black carbomwous material. The coal seams attain 

maximum thickness of 1.2 m. The ash content ranges 19.7% to 

72.9%. The calorific value ranges 3,937-3274 cabkg (Woliela, 

1991). 

Wucbale awl deposit (Wollo) 

The Inter-Trappean cod bearing lacustrine sediments of Wuchale 

is located 62 km hrn Dessie along the Addis Ababa-Asrnara 

rod. The area belongs to the Central Plateau of Ethiopia which is 

largely covered by volcanic &s of trap series (olivine basalt, 

porphyritic pyroxene basalt), The Inter-Trappan coal bearing 

lac-e sedimentary sequence is composed of argillaceous shale 

and clay, menac8ous material (silty sand, sandy silt, sandstone), 

organogenic deposits of (carbonaceous shale, carbonaceous clay 

and cod seams). The sedimentary formation deposited on a 

basaltic substratum bounded by faulted block graben. 

Coal occurrences, mainly lignite vdetim are known to occur in 

m y areas in Ethiopia So far known lignite deposits are located 

in (Gonder, Wollega, Shewa, Ma, Wollo, Tigray and Ham): 

among these, occurrences with esti.nated cod reserves are found 

in: Yayu, Moye, Delbi (1llubabur); Chelga (Gonder, 1 9.7 Mt), Nejo 

(Wollega, 3 M), Wuchale (Wollo, 23 Mt) and Mush Valley 

(Shewa, 0.3 Mt) and are relatively extensive, The available data 

indicate that Yayu, Delbi and Moye coal deposits are more , 

economical than other deposits in the country, with resources 

estimated at about 32 Mt, 20 Mi, and 40.5 Mt respectively (EGS, 

1989). Other coal occurrences where total resewes are not yet 

estimated are found in the lohities: Chida, Jiren, LalwSapo, 

Meteso, Sayoma (Illubabur); Ankober, She, Debre Berhm- Abo- 

Gedam, Debre Libanos, Muger, Mojo, Mojo-Anchano (Shewa); 

Arjo-Kolati, Arjo-Sembo-Nedo, Mendi, Nejo-Kersa, Neja-Koya,

212 Mind Resoufces Potential of Ethiopia 

Nejo-Mecheke (Wollega) and Kindo-Halale, Waka (Omo). Data 

regding these occurrences are just prelhhy obmaiions not 

based on systematic studies and mapping, an; with little 

information about their thicknkss depth extension, lateral 

extension and exploitable m e s . 

Table 10: Important coal deposits of Ethiopia

" ' le 1 ' Other cod (lignite) occurmnces of Ethiopia 

.*' I


Sayoina 

Sehui 

.. ? , . , , , 3 , , , , ,, ,, ? . . ' A : Prospwt j d ~ s i.-Stra!if~m t 

, ,, A A 1

I 

- 

7.13 Oil and gas 

Energy Reso- 21 5 

Natural wits of oil are most commonly found d e d with 

natwal gas (which is itself derived from the heating-up of the oil), 

salt water, and sometimes, sotid hydrocarbons. The process of. 

petroleurn formation involves several steps : 

Organic matter from organisms must be produced in 

great abundance.This organic matter must be buried 

rapidly before oxidation take place; 

Slow chemi-cd reactions -form the organic 

material into the hydrocarbons fourad in petroleum. 

As a result of compaction of the sediments containing the 

petroleum, the oil and natural gas are forced out and migrate into 

permeable rock. Migation is similar to groundwater flow. 

The petroleum must migrate into a reservoir rock 

that is in some way capped by impermeable rocks to 

prevent the petroleum from leaking out to the 

surface of the Earth. Such a geologic structure id 

called atrap. 

All of these processes must occur within a spific 

t range of tempem!mes and pmm.' If higher 

pressures and temperatures are encounted as a 

result of metarnprphism or igneous activity, the 

I 

petroleum will be broken down to other non-useful 

forms of hydrogen and carbon. 

&cause oil and natural gas have a low density they will 

migrate upwards through the Earth and accumulate in a reservoir 

only if a geologic structlrre is present to trap the &roleurn. 

' 

I 

Wlogic structures wherein impermeable rocks occur above the 

permeable reservoir rock are requid. The job of Wleum 

geologists searching for petroleurn moirs is to find conditions 

1 near the Earth's surface where such traps might occur. 

I

, 

2 t6 Mineral R m m Potential of Eihiopia 

Oil traps can be divided into those that form as a result of 

geologic structms like folds and fhults, called structural traps, and 

those that form as a result of stratigraphic relationships between 

rock units, called stratigraphic traps. 'If petroleum has migrated 

into a memoir formed by one of these traps,lt-is important to note 

that the petroleum, like groundwater, wiII occur in the pore spaces 

of the rock. Natural gas will occur above the oil, which in turn will 

overly water in the pore spaces of the reservoir. This occurs 

because the density of natural gas is lower than that of oil which in 

turn is lower than that of water. 

Oil recovery 

The process of ail recovery is essentially the proc,gs of getting oil 

from the places where oil exists in the ground (whether onshore or 

offshore) and into processing plants for rehing so that oil is 

suitable for industrial and residential purposes. The ways to 

recover oil through a conventional well-bore are known as 

p-y, wndary, and tertiary (enhanced), but some 

unconventional methads are dm becoming popular, 

Oil, which is usudly called crude oil in its most basic form, 

is a valuable fuel whose chemical makeup is a mixture of 

hydrocarbon fuels: kerosene, dissolved n W 

gas, naphtha, Iight 

and heavy heating oils, diesel fuel, tars, beme, bd gasoline. It is 

formed over millions of years by the action of heat and pressure on 

organic material buried deep within rock, and typically exists in 

combination with salt water, natural gas, and soil. Most of the 

world's oil comes h m huge, seemingly inexhaustible subterranean 

patches of p us, oi2-permeated rock. The oil is confined to a 

certain location, or "trap," by other layers of impermeable rock 

(usually types of shale) andlor faults.

Top petroleum-produchg countries 

Enerp Resources 2 1 7 

In order of the mount ( hls per day) produced in 2004) top 

petroleum producers are: Saudi Arabia, Russia, United States, 

hq Mexico, C U .Norway, Canada, Venezuela, United Arab 

Emirates, Kuwait, Nigeria, United Kingdom and Ira. Ordered by 

amount exported in 2Q03, top exporters are: Saudi Arabia, Russia, 

Norway, Iran, United Arab Emirates, Venezuela, Kuwait, Nigeria, 

Mexico, Algeria, and Libya. 

Oil and gas deposits in Ethiopia 

The most promising wreas where indicatiom of hydrocarbon have 

been found andlor sedimentary conditions are fhvomble for the 

existence of oil and natural gas includes five main basins; the 

Ogaden, the Gambella, the Ahy (Blue Nile), the Mekele and 

Southprn Rift Basins. Hydrocarbons (oil and gas) have been 

generated in Paleozoic (Bokh shale), Jwic (Urandab Formation) 

an& Cenozoic ~cks (WaW Fmnatioq) and the &entary 

~olurnn-8tfl~ounts over 5,000 m (Getaneh, 1985). Many reservoirs 

are known, bth in Jurassic particularly &&iddie and 

Upper H d e i 

formations, - consisting of grahtone-, packstone, 

bioclastic wackestone and dolomite beds and in pre-Jurassic clastic 

rocks (e.g. the Triassic Adigrat Sandstone and the late Paleozoic- 

early Mtsomic Calub Sandstone), consisting of quartzo-mnite-or 

feldspathic sandstone and mine shale beds. (Getmeh, 1985). The 

followings ar6 description of same of the .better known deposits, 

some of which hot received more attention in recent years. 

Tbe Oga&m Basin 

The Ogaden Basin is located in south-eastern part of the country 

and covers an are of over 350,000 km2 containing over 5,000 m 

thick sediments. The sediments are composed of non-marine to 

deepmarine &tics; thick shallow to deep-marine carbonates and 

evaporates (Ethiopian Ministry of Mine.8 md Energy, 1995). The

' 


most likely oil ,and gas source mks in the sedimentary sequence 

of the OgadekBasin are the BokR Shale and the Hamanlei and 

Uamdab Formations (Getaneh, 1985). The Bokh Shale comprises 

black shale, siltstone and silty sandstone with a few dolostone, 

coarse sandstone and conglomgate intercalations. Its thickness 

changes towards the NE h m 30 m to 690 m. Bokh Shale is 

thought to .represent a deltaic environment. The Hamanlei 

Fodon is a Wlow-marine to lagoonal and deltaic deposit that 

cqnsists of organic-rich carbonate and evapoks with subordinate 

shale and mdstone. The Uwandab Formation is interpreted to be 

a neritic deposit. All three formations, and specially the Bokh and 

Hmantei Formation, contain organic-rich clays, deposited in 

deltaic, neritic and estuarine environments. According to Getaneh, 

the three formations thw meet the general criterion that fine- 

grained sediments deposited in the above mentioned environments 

could be converted to source materials for oil and gas. The Permo- 

Triassic Formation of the Karoo System is known to contain 

mature to over mature shale source rock. Large gas discoveries in 

the Calub and Adigrat Sandstone reservoirs of eastern Ogaden owe 

their origin to the Bokh shale. The Jurassic carbonate particularly 

the Middle and Upper hanlei Formations which are composed 

of grainstone, packstone, bioclastic wackestone and dolomite beds 

have good reservoir. 

A total of 34 deep wells have .been drilled in the basin of 

which 10 are expiomtory, k5 are stratigraphic and 8 are 

development wells of the Calub Gas Condensate Field. As a results 

of the efforts of Ethiopian Ministry of Mines d Enqgy, a 

commercial gas condensate field have been discovered at Calub in 

the Ogaden Basin with enormous reserves estimated over two 

trillion cubic feet or 35 billion metric tons of gas (Ministry of 

Mhm anct Energy, 1995). At the end of 2005, Ethiopia was totally 

ependent upon imports to meet its demand for petroleum. Natural

Enew Resources 2 19 

gas resources in the Calub Field in the Ogaden Basin remained 

undeveloped. Small amounts of lignite were reportedly prduced. 

Petronas Carigali Overseas Shd. Bhd. of Malaysia explored 

for crude petroleum at Block G in the Gambella Basin. In August 

2005, the company was awarded three concessions in the Ogaden 

Basin. Wal-Wal and Wader covered 36,796 square kilometers 

(km); Kelafo, 30.61 1 krn2; and Genale, 25,571 krn2. Petronas 

planned to spend $15 million on exploration in the Ogaden Basin 

starting in 2006 (Ministry of Mines and Energy). In October 2005, 

Pexco ExpIoration of Malaysia was awarded a concession that 

covered 29,865 kmt at Abred and Ferfer in the Ogaden Basin. 

Pexco planned to spend $5 million on exploration over 4 years 

beginning in 2006. In October, 'Afar Exploration Company of the 

United States was negotiating with the Government over a 

concession and production-sharing agreement that covered 1 8,000 

km2 in northern Afar Regional State. 

The Cambetla Basin 

The Gambella area is the south-eastern extension of the Melut 

Basin where two discoveries (Adar and Yale, Sudan) have been 

found. The sediment thickness in the Gambella is estimated at 4.5 

to 5 km. The source interval for hydracarbons in Sudan Basins 

(including the Megulad Basin to the southwest) is Lower 

Cretaceous sediment consisting of predominantly of shale with 

subordinate sandstone. Upper Cretaceous fine to coarse-grained, 

moderately to.poorly sorted sandstone is the main reservoir rock in 

Gambella Currently, the Gambella area is under extensive 

investigation by Petronas Share Co. (Malaysia). 

The Abay Blue Nile Basin 

The ~bay'hsin, which covers a large area over the central northwestern 

Plateau, consists of a thick Mesozoic succession 

exceeding 1,600 m in thickness (Ministry of Mines and Energy, 

1995). Beds of marl, variegated shale and mudstone interbedded

a 

220 Mineral Rwurces Potential of Ethiopia 

with carbonates, and marl limestonecdornimted beds in the lower 

part of a thick limestone unii are potential some rocks in the 

Abay Basin. The most potentid reservoir rock in the Abay Blue 

Nile Basin is the Upper Sandstone which consists of fine to 

medium grained, friable, moderateIy to well-sorted sandstones, 

associated within beds of conglomerates and claystones. Laterally 

restricted oolitic-reefal limestone facies in the lower and upper- 

most parts of AnMo Formation and dolomite beds within the 

mudstone-dominated unit overlying the Antalo Pamation might 

also be considerd as potential intervals in the Mesozoic Sequence. 

The Adipt Sandstone remains a potential reservoir in the Blue 

Nile Basin with characteristics similar to those found in the 

Ogaden Basin, 

The Mekele b i n 

The Mekele Basin has an areal coverage of h ut 8,000 sq km in 

the northern part of the country. The thick Mesozoic sedimentary 

succession of the k in comprises sediments ranging from fluvial- 

lacustrine to deep marine origin. The whole sedimentary sequence 

reaches 2,000 m in thickness. The Upper Jurassic Agula Shale 

Formation, predominantly comprising of shale, rnarlstone and 

variegated clay beds (with limestone and gypsum interbeds) is 

presumed to have good source rock potential for hydrocarbon. The 

Agda Formation (Agula Shale) is thought to be correlative to the 

Madbi and put of the Ndh fmmations of the Yemen Gulf of Aden 

region. The tramgresive to braided-fluvid sandy Adigrat 

Formation, with a thickness ranging between 150 m to 600 m of 

medium- to course-grained, greyish-white to pink-red sandstone is 

a potential reservoir; as it is in the Ogaden and Blue Nile Basin. 

The Southern Rift Basin 

The Omo and Chew Bahir Basins lie within the broadly rifted zone 

of Southem Ethiopia bordering Northern Kenya. The possible 

existence of sediments of a Jurassic-Cretweous riR system

underneath the Tertiary rift strata is also possible. Organic-rich oil 

shale with an average oil yield of 8 lidton. occurs in a regionally 

WSW-ENE extending Tertiary basin in the northern part of the 

Southern Rift basins (Ethiopian Ministry of Mines and Energy. 

1995). Other basins are less explored and have scarce data with 

. respect to hydrocarbon potential. The whole Ogaden Basin (S-E 

Ethiopia) has both potential for oil and gas. 

\ 

- 

Qwo 55 hqwdvo sadimsnEary bins ofEtbioph ((Etbpb of Mines 

7.1.3 Oil shale 

Oil shale is considered to l>e formed by the deposition of organic 

matter in lakes, lagoons and restricted estuarine areas swll as 

t ard 8neagy, 1995).

222 Mind Resources Potential of Ethiopia 

oxbow lakes and muskegs. Generally, oil shales are considered to 

Ix formed by accumulation of algai debris. 

Oil can be extracted from oil shale, but they must be heated 

to high enough temperatures to drive the oil out. Since this process 

quires a lot of energy, exploitation of oil shale is not currently 

cost-effective, but may become so as other sources of petroleum 

become depleted. Known deposits of oil shale are extensive, 

Unlike coal, oil shale does not necessarily require low mineral and 

ash content, as it is not used for burning, and mineral waste in oil 

liquefaction plants is easier to deal with. Eventually, and usually 

due to the initial onset of orogeny or other tectonic events, the 

algal swamp-forming environment is disrupted and oil shale 

accun~ulation 

ceases. Oil shale is known as 'rock that bums'. 

Oil shale occurrenm in Ethiopia 

Oil shale is said to occur in the south western P h u of the 

a country and between Lake Ziway and Lake Abyiata in the valleys 

of the Bulbul River and its tributaries. The fluvid-lacustrine oil 

shale bearing formations of Delbi, Mefeso, Lalo-Sapo, Solo, 

Soyoma, and Mojo-Anchema are an Inter-Trappean continental 

sedimentadon on the south western Plateau of Ethiopia. The 

deposits occur intercalated within Cenozoic volcanics. The oil 

shale is characterized by high ash contents, low calorific value and 

low fixed carbon. The Pelbi oil shale has a fixed carbon ranging 

from 27.6%83,0% and a calorific value r&iging from 58 1-6,165 

kcalkg. Recent drillidg data proved the presence of 1W120 

million tons of oil shale deposits at Delbi (Wolela, 199 1 ; 1995). 

No details are known for the Bulbul River deposits. 

7.2 Geothermal raources 

Geothermal energy resources result from complex geologic 

processes that lead to heat concentration at accessible depths. The 

different forms of gmthermd energy resources-hydmthed, hot

En- Resowlew ~3 

dry rock, geopressd, magma, and earth heat-all result from this 

concentration of earth's heat in discrete regions of the subsurface. 

Temperature within the earth increases with increasing depth. 

Highly viscous or partially molten rock at temperatures between 

650 to 1 ,2W°C is postulated to hist everywhere beneath the earth's 

surface at depth of 80 to 100 kms, and the temperature at the 

earth's center, nearly 6,400 kms deep, is estimatsd to k 4,000°C or 

higher. Heat flows constantly from its sources with the earth to 

the surface. 

Three sources of internal heat are most important; (I) Heat 

released hm decay of Murally radioactive elements; (2) heat of 

impact and compression released during the original formation of 

the earth by accretion of in-falling meteorites and (3) heat released 

fiom the sinking of abundant heavy metals (iron, nickel, and 

copper) as they descended to form the earth's core. An estimated 

45 to 85 % of the heat escaping from the earth originates from 

a radioactive decay of elements concentrated in the crust. The 

remainder results from slow cooling of the earth, with heat being 

brought up from the core by convection in the viscous made. 

The different forms of geothermal resources have different 

characteristics that are important to geothermal energy 

development: 

- Hydrothermal resources are steam or hot water reservoirs 

that can be tapped by WlIing to deliver heat to the surface 

for t hed use or generation of electricity. Technologies to 

tap hydrothermal resources are proven commercial 

processes. Dry steam resources are relatively rare; 

- Hot dry rock resources are defined as heat stored in largely 

impermeable. Access to these resources involves fhcturhg 

rock injecting cold water through one well, circulating it 

through the hot fractured rock, and drawing off the now 

hot water from another well. Since the current technologies

124 R.1 incral Resources Potential of Ethiopia 

- 

are entering a developmept phase, this is not a commercial 

process at this time; 

Geopressured resources consist of deeply buried brines at 

moderate temperature that contain dissolved methane. 

Three sources of energy are available: thermal, 

' 

I 

a mechanical, and chemical (methane gas). While 

I 

technologies are available to tap geoprwsured brines, they 

I 

I 

- 

are not currently economically competitive. No funds are 

currently being directed toward accessing these resources; 

Magma (molten rock) resources offer extremely hightemperature 

geothd opportunities, but existing 

technology does not allow recovery of heat from these 

- 

ra0UtT:es; 

M h heat itself can b used as the source and/or sink of 

heat for the operation of geothermal heat pumps-a proven 

technology. 

Geothermal -11- in Ethiopia 

Geothermal systems produce inexhaustible aatural steam in 

contrast to coal-fired plants or nuclear plants that generate steam 

by heating water in large boilers. The pressure of fast flowing 

water or steam released against the blades of a turbine rotates its 

shaft which is also connected to an electric generator. In the 

generation of electricity, mechanical energy is transformed into 

electrical energy, The transformertion makes use of the ability of a 

rnovi~lg magnet to induce electricity in a conducting wire. 

Basically, a magnet around which a copper wire is wound is 

attached to the shaft of a turbine. When the turbine rotates, the 

magnet is moved and electricity is induced (generated) in the wire. 

The electrical energy can be distributed to perform mechanical 

tasks, via suitable motors, such as pumping water for irrigation, 

drilling tunnets for roads, railroads, etc., and, of course, for 

producing light.

Y 

I 

Resources Potential of Ethiopia 

htbemal explor6~tion and dwelopment in Ethiopia 

Ethiopia started longterm geothermal exploration undertaking in 

1969. Over the years, a good inventory of the possible resource 

areas has been built up and a number of the more important sites 

have been explored. Of these areas, about sixteen geothermal 

1 pros- areas are judged to have potentid for high temperatrire 

steam suited to electricity generation (Meseret et al., 2000). A 

much larger number are capable of being developed for non- 

electricity generation applicatiois in agriculture, agro-indw, etc. 

Exploration work peaked during the early to mid-1980s when 

exploration drilling was carried out at the Auto-Langano 

geothermal field. Eight exploratory wells were drilled, of which 

four are potentially productive. During the early 199Os, exploration 

drilling was also &ed out at Tendaho. Three deep and three 

shallow wells were drilled at the Tendaho geothermal field, and 

. proved the existence of high temperature and pressure fluid (EGS, 

1989). Based on the results of the investigations, Ethiopia could 

possibly generate more than 1,000 MW of electric power hxn 

geothermal resources alone. This is substantially in excess of its 

d requirement of around 700 MW hm all energy sources for 

current Inter-connected and Self Contained Systems (Mesera 

zF 

The followings are descriptions of the better known deposit 

hich has received more attention in recent years. 

lu to-Langano geothermal fleld 

he Aluto-hgano geothermal field is located on the oor of the 

thiopian Rift Valley about 200 km south-east of Addis Ahba. 

e Aluto volcanic complex "i a Quaternary volcanic center 

ted along the Wonji Fault Belt in the central sector of the MER. 

geology of this complex is relatively well-known from surface 

supplemented by data on the deep stratigraphy and 

from eight deep exploratory wells that were sunk to

R- 227 

depths ranging from 1,300 to 2,500111 by EGS. In the Alum- 

Langano geothermal field, eight deep exploratory wells were 

Med to a maximum depth of 2,500m Mmen 1981 and 1985, 

out of which four are potentially productive. The maximum 

memoir temperature encountered in the productive wells is about 

350°C. A feasibility study was conducted by an Italian fmn; 

Electro Consult, between 1983 and 1986 (BE, 1986). The study 

revesried tbat in the Aluto-Langmo, the capacity of the existing 

deep wells is close to 30 MWatt; the energy potential of the field is 

estimated between 10-20 Mwekm-3 for over 30 yews (EGS, 

1989). A 7.3 MW pilot geothermal plant was installed in 1999 

utilizing the exploration wells that had been drilled.

228 Mineral P O W of Ethiopia

! 

The M aha geothermal field 


The Ten- graben is found further north in the Afar depression. 

It is a NW-SE trending graben about 50 km wide and is the 

southem extension of the Afar active spreading zones where the 

active Erta Ale-Man& Hararo volcanic ranges are situated. At 

Tendaho, between 1993 and 1998, three deep (to a maximum depth 

of 2100 m) and three shallow explotatory wells (up to 500 m) were 

drilled that found a temperature of over 270°C. The capacity of the 

existing producing wells in Tendaho is about 5 MWatt (Aquater, 

1996). 

Corbetti geothermal prospect arq 

The Corbetti geothermd prospect area is located about 250 km 

south of Addis Ababa. Corbetti is a Holocene volcanic complex 

found in the central sector of the MER. The most abundant 

volcanic rocks are peralkaline pyroclastics (ijyimbrite and pumice) 

which are attribuFd to central-type eruptions with subsequent 

volcano-tectonic collapse. Corbetti is a silicic volcano system 

within f 2 km wide caldera that contains widespread thermal 

activity such as fumaroIes and steam vents. Detail geological, 

geochemical and geophysical investigations conducted in ~o&tti 

area indicated the presence of potential geothermal reservoirs with 

ternperatwe in excess of 250°C. Six temperature gradient wells 

have been drilled to depths ranging from 93- 178 m, A maximum 

temperature of 94°C was recorded, 

Abaya geothermal pmpect area 

Abaya is located on the northwest shore of Lake Abaya, about 400 

kms south by road from Addis Ababa, The Abaya prospect 

exhibits a widespread thermal activity mainly characterized by hot 

springs, haroles and dtered gmunds. Spring temperatms are as 

high as 96OC with a high flow rate. Integrated geoscientific studies

230 Mineral Rwurces Potential of mhiopia 

(geology, geochemistry and geophysics) have identified the 

existence of a potential geotha reservoir with temperature in 

excess of 2M°C (Ayele et al., 20021, 

Tulu MoyWemsa geothermal prospect area 

The area is characterized by volcanism dating from Recent (0.8- 

0.08 Ma) to historical times. The area is highly dfkcted by 

hydrothermal activity with the main hyhtheml mmifkstdon 

h g 

weak fumaroles, active steaming grounds (60-80°C) and 

altered grounds. The weakness of the hydrothermal manifestations 

is explained as being the result of the relatively high altitude of the 

prospect area and the considerable depth to the ground water table. 

Dofan geothermal prrwspect area 

The area is locat4 about 40 km distance from the high voltage 

substation in Awash town. T'he presence of several hydrothermal 

manifestations (fumaroles and hot springs) within the graben 

' together with an impervious cap needs to be regarded with high 

priority for further detail exploration and development. 

Fantale geotbed prospect area 

The Fantale geothermal prospect is characterized by recent summit 

caldera collapse felsic lava exbusions in the caldera floor and 

widespread of fumaroles activity suggesting the existence of s 

shallow magma chamber. Prospects of geothermal energy at 

recomahame level include Kone, Meteka, Dmab, Teo and Lwke 

Abe geothermal prospects. 

Prospects at mconnabanw Level (Kone, Meteka, Danab, Teo and 

L. Abhe geothermal pmpds) 

During the 1 980s, reconnaissance geological, geochemical and 

geophysical investigations had been conducted in these areas and 

revealed the existence of young volcanic features and active 

s& thermal manifestations. Me@a-md Teo hold promise for 

the discovery of economically exploitable g eothd resources at

1 


high temperature and warrant detailed surface investigation, 

followed by exploratory drilling. 

Current Geothermal Activities in Ethiopia 

b 

The status of on-going geothermal activities in the Geological 

Swey of Ethiopia (GSE) is: (i) Monitoring (geochemical and 

mervoir engineering) of the Tendaho geothermal field (Dubti); (ii) 

Detailed geologicd mapping, geochemical and geophysical studies 

of the Southern Afar area (e.g. Dofan and Fantale etc.); (iii) 

Collection of water samples for isotope, chemical and gas analysis 

hm surface geothermal manifestations mmd Main Ethiopian 

Rift, Southern Afar and Northern Afar regions. 

Detail integrated geoscientific studies of the Lakes District 

area, particularly in the Corbetti and in the southern Afar 

geothermal prospect areas of Tdu Moyffiedemsa have confirmed 

the existence of exploitable geothermal resource and delineated 

a target areas for further deep exploratory wells. Currently, detailed 

geological, gemhemid and geophysical studies are underway in 

the Dofan-Fantale geothermal prospect areas of the Southem Afar 

region. Other prospect areas of this region (Kone, Meteka, Teo, 

Danab and Abhe, etc.) and in the Northem Afar (Ddlol, etc.) are 

yet to be explored in detail. 

Future programs of geothermal exploration and 

I development shall be based on considerations of logistic and socio- 

I economic framework of each prospect. Therefore, each of the 

prospects is qualified with respect to the probability of having an 

I 

economically viable geothermal resource. Acoording to Mesat, 

p 1991, other than Aluto-Langanb and Tendaho geothermal fields, 

the following are a list of prospects in order of the level of 

exploration: 

- Advance exploration stage; Tulu-Moye, Gedemsa and 

Corbetti; 

- Detailed investigation Completed, Abaya;

232 Mind Resources Potentid of Ethiopia 

- Detailed investigation ongoing; Dofan and Fantale; 

- Reconnaissance stage; Kone, Meteka, Danab, Teo and 

Abhe. 

Energy is an important element in Ethiopia's development strategy, 

because it could be a source of foreign excbge and is a catalyst 

for industrial progress. Ethiopia has a diversity of modern energy 

sources (hydro, geothermal, solar, natural gas, etc.), but still relies 

on imported petroleum and petroleum products, Energy 

consumption in Ethiopia is made up of less than 1 % electricity, 

about 5.4% hydrocarbon fuels and the balance, traditional biomass 

fuels (EEPCO Data File). Currently, about 90% of the rural 

population still relies on traditional biomass fuel (wood) as their

238 Mineral Resources Potential of Ethimia 

Gordma, and hemetal prospects of volcanogenicvolcano 

sedimentary type (AbetseIo, Kata); 

- a northern domain (Tigray) extending northwards towards 

Erika, composed of several metamorphic metavolcanosedimentary 

belts and sub-belts, bounded by m&cuItramafc 

rocks, hosting gold and base-metal occurrences 

(e-g., Adi Zeresenay, Au). 

Significant metallic mineral sites l o w outside of these domains 

are rare, and include the Melka Arba iron deposit (basic intrusionrelated), 

the Chercher copper deposit (Red Bed type in Mesozoic 

sandstones) and the Edcafah manganese deposit (Plio-Pleistocene 

sediments of the D 4 depression). 

Industrial minerals and rock resources occur in more 

diversified geological environments, including the Proterozoic 

basement rocks, the Late Paleozoic to Mesozoic sediments and 

recent (~zoic) voIcanics and assooiated sediments. The 

occurrences of energy resources (oil, mtmd gas, coal, geothermal 

resources) are restricted to Phaneromic basin sediments and 

Cenozoic volcanism and rifting areas. 

The discovery of the primary gold deposit at Legadembi 

(Southern Ethiopia), which has mched a production stage, can be 

cited as the best example of the significance of systematic 

exploration conducted in the recent years. Furthermore, the recent 

discovery of eluvialdeluvial gold in western Tigray (Adi Daro, 

Asgede and Daro Techi) and fie Werri gold and base metals by 

Wemi Gold Project (NMIC); discoveries of gold and base-metals at 

1dities Gale Repwr, Awm, Epbo (Bden, Benishangd 

Gumuz) and Boseti locality (Adola); gold deposit at Okote (Dawa 

Digati area; currmtly under intensive exploration by bore holes) by 

Midroc Lega Dembi mineral exploration project; and base-metals 

(copper) and gold occurrences of WacRile and Gewle in Arero 

Womda, Borena zone (Southem Ethiopia) by the Ethiopian

Summary and concludons 

The aim of this book is to cumpile in one volume a digital 

geoscientific database with maps for geology and mineral and 

energy resources of the country. The book is comprehensive but 

general in its treatment of topics, and it is hoped that it will be of 

wide interest to both scholars and general public. This synthesis 

gives an up-- compilation of Ethiopian mineral resources 

(location, description) in their geologid context (metallic 

minerals, industrial minerals, construction and building materials, 

gemstones, and energy resources). 

The metamorphic metavolcano-sedimentmy belts and 

associated intnrsives belonging to various terrain of the Arabo- 

Nubian Shield, welded together during the East and West 

Gondwma collisional orogeny (Neopmteromic, 900-500 Ma), host 

.yarious metallic resources (precious, rare, base-and ferrousf~aloy 

metals). According to the repartition of these belts, 

regional distribution of metallic mind resources shows three 

distinct domains: 

- a southern domain, including the metamorphic 

metavolmo-sedimentary of the Adola and Kenticha belts; 

this domain hosts major primary gold deposits (e.g. 

Legadembi gold mine, Megado, Sakaro, Okote-Dwwa 

Digati), the main Ethiopian gold placer deposits (Adola), - 

the pegmatite-hosted Kenticha tatlute mine and the 

mndary laterite-related nickel deposits of the Adola 

district. Other isolated primary gold deposits under 

reconnaissance are known 200 km southwards, close to the 

Moyale town and the Kenyan border (e.g. Haramsam, 

Hasamte); 

- a wide western domain, following the Sudanese border; 

this domain can be subdivided into four belts, hosting 

'primary gold deposits (e.g. Dul, Oda-Godme), the Yubdo 

platinum deposit, the iron deposits of BiliKal, Chago,

Mineral Development Sh. Co are g d 

Summary and conclusions 239 

indicators of the mineral 

potential sf the country for gold, h-metals and other deposits. 

In this &, a wide range of mineral distribution in the 

basement d of the southern, western, and northern periphery of 

the country invites finma -mematic exploration walr to locate and 

deli- different minerd reso-. Furthermore, recent discovery 

of strong gold anomalies in the Ethiopian Rifi in the localities of 

Tend&, Corbetti, Gedemsa and Aluto suggests the possibility for 

further potential economic mineral resources within the rift floor. 

A new field of investigation on epithermal ore occurrences which 

are unusual for the present Ethiopian metallogenic picture is 

emerging. A study of these phenomena, in light of recent 

acquisitions of metallogenic knowledge, could be of interest not 

only for further scientific studies but also for new possibilities in 

mining activity. The unique situation of the East African Rifts, not 

yet considered as a possible site for this kind of mineralization, 

'should be carefully tested. A fascinating field of mineral 

prospecting can be envisaged in these wide volcanic areas of 

Ethiopia and other East African countries. All these ment 

discoveries in different parts of the colmtry confirm that the 

metallogmy of Ethiopia has a significant and potential importance, 

greater than the small recorded mineral production wodd suggest, 

and justifies Wer work which will contribute to unraveling the 

complex geology of the country and its associated mineral potential. 

Following the above, the Adola area belongs to a me- 

metal metallogenic province, the only one so far known in the 

horn of Africa. However, this rich mineral wealth has not yet been 

fully explored and utilized. The pment knowledge about the 

Kenticha rare-metal belt is limited to a previous economic 

evaluation, which was largely based on preliminary geological 

approaches, Hence it is necessary to carry out a detailed 

investigation to understand the genetic aspects as well as the 

pattern of rare-metal enribkt for each area including the

@ G;' 240 Mind Resou- Potential of Ethiopia 

regional distribution of the tant&m min&dization. Development 

of exploration strategies and identification of reserves should be 

done on a continuing basis. 

It is known that Ethiopia is endowed with suitable 

geological environments to host all varieties of gemstone, although 

this has not yet been investigated in detail. Nevertheless, 

gemstones (e.g, beryl, stquamarine, tourmaline, garnet, spinel, 

tom chalcedony, agate, jasper, petrifa wood, chrysoprase) are 

reported to occur in Sidamo (Kenticha, Kibre Mengist area), 

Harrar (Babile, Jijiga: amethyst, garnet), and Tigray (Axum and 

Adwa area: amethyst, agate, chalcedony). There are plentiful 

indicators of the presence of a variety of gemstone deposits in the 

countq, including ruby (Kibre Mengist area), sapphire (Dilla 

area), emerald (Cheri, Fulana, Moyale), and diamond (Turmi, 

Moyale). Gemstones are, therefore, regarded as one of the rich 

mined resources of the country, though little is known about their 

occurrence. Therefore, systematic exploration is required to assess 

the gemstoms potenti J of the counEry. 

- 

presently, there is a very widespread illegal trade in 

gemstones which are being smuggled out of the country. The 

gemstones involved in illegal transactions include opal, beryl 

(emerald, aqdne), conmdm (ruby md -1, garnet, 

tourmaline, @te, @dot and even diamond. It is also known 

that numy smugglers were not willing to give any 

indication as to where the gem came from, which is crucial, 

considering the urgent requirement to reduce illegaI trading and 

smuggling of unprocessed gemstones, particularly opal, ruby, 

sapphire aquamarine and others. 

.Ethiopia posseses dl the requirements of a pehliferous I 

region. Hydrocarbons (oil a d natural gas) have been identified in -8~ 

Paleozoic (bkh Shale), Jurassic (CJrandab Formation) and 

Cenozoic rocks (Habab Formation); and the sedimentary column 

mounts to ova 5,000 meters. Many reservoirs are known, both in @; 

,

Summary and conclusions 24 1 

&nates (Lower Hamanlei Formation), and clastic rocks 

(Adigmt Sandstone and Kalub Sandstone), and various types of 

traps are probably present. However, detailed s ubshe studies 

combined with geophysical methods are essential to further 

success in the discovery of commercial accumulations of 

hydrocartans in Ethiopia. 

The diversification of energy resumes is essential in order 

to ensure sustainable energy supply. Therefore, geothermal power 

needs to be developed to help' replace import of fossil fuel; to 

provide a major backup to ari uncertain availability of hydropower; 

and for use in arid and semi-arid anas of the country where 

hydropower is unavailable. Furthermore, emphasis should be 

p k d on exploitation of geothermal energy, afforestation of 

drainage basins, and improvement of agricultural methodologies. 

To conclude, most of the country's mineral mource 

occurrences have been examined by local wnd foreign geologists, 

but it would be premature to say that there are no further deposits 

of useful mineral resourca awaiting discovery, A comparatively 

small part of the country has been geologically mapped 

systemeltical1y. Geological maps at scales between 1:100,000 to 

1 :25,000 should be prepared for areas where mineral occurrences 

elre to be prospected for, and where known deposits are to be 

developed or exploited. S ystqatic organization of the available 

geological database is needed as well as the establishment of an 

easily accessible National Geological Data Bank (NGDB), which 

wodd aid the discovery of economic deposits within reasonable 

time-frame. The relevant authoritied institutions should put more 

investment to promoting the mi@ wealth of the country, as the 

minerals industry is a highrisk and capital-intensive sector that 

cannot be developed by local capacities.

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252 Mineral Potentid of Ethiopia 

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-1 

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254 Mineral Resouroes Potential of Ethiopia 

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L-' r j ..&L;jg.Tdt:svn ++~=;,J:~@+#~~ 

;g ~ 3 ~ q ~ , r ~ 

3 

. b- -;3&? =- w 

w 

f'q* 

rL xL,

Rtfmnces 255 

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Annex 1. Major mineral deposits of Ethiopia (A, B & C Class)

258 Mineral kurces P o t d of Ethiopia

260 Mineral Resources Potential of Ethiopia


' Annex 2. Minor mineral deposits of Ethiopia (Class D, E, NIA)- 

I NAME I IDENTIF. I SUBSTANCE I CLASS I X-LO~ I Y-L*~ I 

Arero Town I ETH-00028 I U I E 1 38.80- 1 4.70 

Wadera ETH-00030 u, I'Ph E 36.35 5 67 

Sun~ppa ETH-00031 U E 38-35 5.17 

- Sernbaba ETH-00032 U E 38.85 5.85 

ppp -- 

: helm ETH-00033 U E 35.35 f.35 

Harm ETH-00036 Nb, Th,U A 42.01 9.35 . 

Wellega ETH-00038 Fe D 35.11 8 71

I 

1 

NAME 

Afa (Dabw Insin) 

Ahtu 

Aflata placer (Au) 

AM8 - b wa 

A & m m 

Agheremarism (Au) 

IDENTIP. 

ETH-00229 

ETH-00230 

ETH-0023 I 

- 

ErHd0233 

ETH-ooull 

ETH-00235 

SUBSTANCE 

Alanp 1 mH40242 1 Au I NIA ] 35.09 1 6.80 

A0 

Pb 

Au 

All 

Tlc, Asb 

A% cn 

' C W 

AWa 

ETH44236 An NIA 34.41 

A h ETH.oM37 Ft MA 35.36 ----a 

ITH-MDD Au, Cu D 33.21 

AkOb (a) 

ETH60239 1 AuCu.Pb, Zn 

Alaltu I ETH-OOZ41 I Au 1 D 1 3 5 3 1 9.51 

Alfe (Birbirl basin 

Ankh 

As8edo 

Aslwliim 

b k Akendayu 

- 

ETH-OLI244 

ETH-46 

ETH-aO247 

ETH-00250 

ETH4025 1 

NIA 

NIA 

N/A 

N/A 

WA 

NIA 

%& 

3839 

NIA I 35.22 1 5.99 

Awata Terrace 1 ETH-OD254 I Au 1 E 1 38.82 1 5.% 

Babik - Bob 

hda knwda 

I'WI~U 

AU 

Fel d 

Cu 

Au 

l3II40255 Au NrA 

kmwo I ETH40256 I Ti I MIA 

Bnlr 

m 

Bam 

Bedakesna 

: - p l - ,,, L-. .; 

I 

Belawch 

Bdet w~rm 

ETH40251 

ETH-00258 

nli-00159 

EM-00261 

ETHm162 

ETHm63 

ETH-00267 

ETH- 

ETHm- 

- . ..4$%~3?Xi$:;. 

i ,- : ,*,. t&., :' .- -!4&,-.;. - - i,: L-i * -L. . Y.>, , ; 0.. .g. : ', -. 

Au 

Au 

** ~Cu.Co. 

W 

Ni 

Au 

Au 

Au 

Pah 

E 

WA 

NIA 

NIA 

NIA 

D 

NlA 

WA 

WA 

E 

NIA 

E 

NIA 

MIA 

3825 

35.44 

39.67 

M.29 

38-13 

Annex 263 

5.23 

5.23 

5.55 

10.00 

9.07 

6.46 

k.99 

9.59 

14.41 

14.07 

34.43 10.49 

35.62 

34.36 

33QI 

/ 

38s' 

34.41 

4,8t 

11.02 

9.69 

8.25 

5.8 1 

lo.% 

4.98

266 Miml b u m Potential qfj Ethippia , . 

NAY E IDEWnP. ' SUaffAMCC ClAS. ~ih Y-M 

Ebircha - Okde 5+08 

El Sod l3H-00368 Au NIA 3&40 4.20 

E k ~r~00369 Say NIA 41.81 . 3.14 

Eloda Gamm ETH-00371 Salt Plla 39.56 14.23 

Eaidio (Ft) ETH-00372 M MA 39.12 1423 

E~iticl~o (BM) . ETH.00373 Fe NIA 39.15 14.48 

Eniclo{Cu) - li3lMO374 BM WA 38.% 14.24 

-- 

Entoto ETH-73 s Cu NIA 38.77 8.97 

Erm Rim 1 ETH-376 I Ft 

ETH - X-35 

Fena Mah!o ETH-00381 

Gq~wnr - Fm403tf Few, SIC E 38.80 536 

Galsdi 1 ETH-00388 ! Au NIA 1 46.28 I 6.82 

-ti ETH40- Pen I3 40.79 &58 

Gaktli Valley (Cy NI, Co) ETH403W hl I D 10.92 4.07 

Wmi Vnlky (FBI ETHWI Cn,Ni,Co 'NIA 41.14 9.01 

Gmbeln Mournin ETH-00392 Fe NIA 34.41 10.66 

Gambo ETl.00393 Au NIA 35.51 9,SO

Gaada 

GLidmol 

a i i 2 

Gbimira bkn 

Gima ' 

Ell-MMOS 

lillwM07 

ETH.00408 

E T M 

ETH-OQIO 

GmAu 

Salt 

G&NI , 

ETH.OWI 1 P#r NIA 

Oddare 

E'tH-00412 U 

E ------ 

Oodioho 

ETH4M13 

Au NIA 

Goma (EM) 1 ETH-00414 

Gm 

- 

n G,uba (Mrbl) 

ETH-004 17 

G&a (Fe) ETH-004 19 

Ouk ETH-23 

Au 

3~ ' 

GwdPma (Au) I ETH-00418 I Au I NIA 1 35.54 1 8.96 

Gudba Valley 

ETH90424 

Fa 

SdI 

NIA 

NIA 

NIA 

WA 

All 

E 35.54 8.77 ---- 

35.28 10.27 

Fa 

Mrbl 

NIA 

41-44 

35.31 

35.21 

%at 

AU E 38-87 

Oudubsa 1 ETH-00425 I Be I A 1 38.12 1 5.36 

Fe 

NIA 

D 

N/A 

NIA 

36.74 

41.93 

35-17 

37.76 

35.69 

37.27 

636 

9-15 

632 

7.02 

7.5 1 

864 

1.43 

6.22 

8.8 

3.74 

7.59 

38.89 5.68 

An NIA 40.09 5.66


Hiniali 

Hocdu 

Hola bridge 

NAME 

IDEATIF. 

~$~-00441 

ETH-004.12 

ETH-00443 

SUBSTANCE 

Hala - Kuni I ETH-00444 I Mrbl, Do1 I D 1 42.20 ] 9.10 

Hunk-Blesnma 1 ETH-00115 I Coal I N/A 1 41.48 1 9.52 

Ijabuna I ETtI-00446 I Pb,Cu ( NIA 1 41.88 9.56 

Imei 

Jaja Valley (Cu) 

ETH-0044 7 

ETH-OW8 

Jaj- Valley (Gr) 1 ETH-00419 I Gr NIA 1 38.70 1 9.05 

Jibota I ETH-00450 I Au I E 1 34.05 1 5.83 

Jire~i 

Kajimiti I 

Kajimiii 2 

Kalamis 

Katawicha 

Kebre Me~~gist (ClyC) 

Kebre Me~~~ist (Coal) 

Kelecha 

Kenticha (Fc) 

ETH-00451 

ETH40454 

F.TH-00455 

ETH-00.156 

ETH404M 

ETH-00466 

ETH-00467 

ETH-00468 

ETH-00469 

Cu 

Salt 

Silc 

Salt 

Cu 

Coal 

Au. Zn. Co 

Au, Zn, Cu 

CLASS 

NIA 

NIA 

NIA 

NIA 

NIA 

X-Lon 

41.49 

39.38 

41.1 1 

41.17 

41.15 

k'-Lat 

Korkoro ] ETH40483 I Au. Pb, A& W I E 1 38.88 1 5.71 

Kumtidu I ETH-00485 I Au I NIA 1 38.90 1 5.70 

Kunni 

Kunni Valley (CL Ni, Co) 

Kun~ii Valley (Gr, Dol) 

ETH4048G 

ETH-00487 

ETH-00488 

Salt 

Ni 

C1$+ Silc, Mica- 

I 

Coal 

Au 

Fe 

NlA 

NIA 

D 

NIA 

NIA 

N(A 

NtA 

E 

N/A 

38.76 

38.81 

41.40 

35.01 

38.88 

38.84 

38.84 

39.18 

----- 

Fe 

Cy Ni, Co 

Gr, Do1 

NIA 

D 

N!A 

35.49 

14.43 

5.62 

4.80 

6.56 

9.20 

7.70 

5.59 

5.49 

6.55 

5 29 

5.75 

5.90 

5.90 

5.19 

40.94 8.94 

40.84 9.06 

80.79 8.74

- - 

NAME IDEhTlF. SUBSTANCE 

Lake nbrOg (GTH) 

Id8 Giulieh 

L~P hH 

Lega Dima t 

Le Dima 2 

, LegaG-2 

WGwhe I 

ETH4W489 

ETH-004W 

ETH40500 

ETH-WIO 

ETH-005 14 

ETH9M 15 

ETH.005 16 

ETH4D5 17 

GTH 

Au 

Au 

CLASS 

Likt ETH905 19 Ft NIA 37 -29 1.49 

Maji I ETH-OM23 ) ClyC I NIA ) 35.10 ] 6.54 

Salt 

NIA 

NIA 

NIA 

NIA 

35.51 

38.86 

Lena Gaa 1 ETH-WS!S I Au I NIA 1 38.83 1 5-37 

Malca Ho~na 

Maldu-.4l& 

Marism A& hs&i 

Mmwa 

MeMm, Adi Hay 

ETHM1524 

ETH-00525 

ETH-00328 

ETH-00529 

ETHbOS3 I 

Au 

Au 

Au 

Cu 

Au 

Zn. Pb 

Asb 

Au. BM 

E 

E 

NIA 

NIA 

NIA 

NIA 

NIA 

NIA 

38.11 

41.01 

38.80 

38.68 

58.80 

38.76 

38.83 

39.49 

40.68 

3B.11 

6.70 

13.40 

8.97 

5.76 

5.76 

5.83 

5.79 

5.32 

5.93 

13.98 

14,M 

14.70

270 Miml Resources Potential of Ethioaia 

Mellu A h ETW0053B Ft, Ti, h s D 

k Guhb 1 Par1 I ETH-l I h I NIA 

Matefinfin {-) EllUHB42 Au.Cn.W NIA 

Mct~m ETH40.543 C d NJA 

Md ETH 40544 Au NIA 

Mag Ial EM.00545 Aab MA 

*(w) ETH-00546 CIS NIA 

*(Coal) ETH-7 Coll WA 

M o j o - A ~ ~ mH-O(H48 Cml WA 

Fmio m~a0552 h MIA 

McumlmkTankua ETHoM53 Cad NIA 

Mayale pmpcrty (Chnmuk, 

Lwo Riw ~~~-00578 Ti, V, W 

ETH90579 

m a r ETHa81 

ETH.00382 Au, Cu WA

NAME I 

Sam (Ni) 

Ss-w 

IDENTIF. SUBSTANCE CLASS X-ton 

ETl.CODj83 N1, Co, Cu E 39.1 1 ----- 

E m & Au. BM FUA 39.14 

Sawana ETH-OOSSS 

-- 

Au E 

*ma ETH4058G Coal NIA 

. .. 

Sebeaa mH-589 0s NIA 

Sdni ETH-00588 Coal NIA 

Shski 

ETH-0059 1 

Fe NIA' ------ 

% 

ETH-92 

Au D 

Shebdli 

Shlnlle 

Shirgtlo 

S~OOU~ 

Srmll rhhkha 

Gem 

ETH40M 

ETH-00595 

ETH-[X)S% 

-597 

ErH4599 

ETH-006W 

Wdu I ETH-00601 I PWAu I D 1 35.49 I 9.08 

M r o I ETH-00602 I ClyC ( NIA 1 N.19.59 1 8:10 

-(PC) 

Sdcll (Gr, MDd) 

Subaha 

(Pb, Q) 

iTH-00603 

lXKOD60Q 

Taw Riwr ETH40607 

Tdid Rim 

' T W W 

Tsslfa nnd Ulak 

lZTH4nM5 

ETH-00606 

Mi= 

LtC, M;bl 

Au 

Au 

Ni 

Au E 

Annex 271 

Y-ht 

13.1 

Tlllu Gokl 1 ITH-aoa21 I Co I NIA 153.67 1 9.43 

. -- 

Tulu Kmi - Njo 

ETH--2 Ail, Be MIA 35.50 9.70 

Ft 

Or, Ool 

Fb, Cu 

NJA 

NIA 

NIA 

NIA 

NIA 

38.63 

38.91 

42.42 

41.F 

34.44 

3468 

39.05 

38.01 

3.59 

Au NIA 37.46 14.14 

T& I lTH40609 I Au I E 1 38.m 1 5.63 

ETHQ061I 

ETH-12 

ETH-00613 

Asb 

Cu 

Cu.Zn 

Au 

- 

WA 

NIA 

HIA 

WA 

WA 

NIA 

NIA 

41.4s 

' 41.32 

41.33 

39.69 

38.94 

38.47 

34.44 

5-22 

5.79 

9.01 

9.73 

9.88 

10.60 

5m 

552 

9.14 

9.17 

9.26 

14.36 

13.81 

13.73 

9.77


NAME 

Tdu Kspi (Birbir k in) 

IDENTIF. 

ETH-23 

SUBSTANCE 

Au, Ag, Cti 

CLASS 

Wdm ErllauCl Coal NIA 37.13 7,M ----- 

W m E T W I An A 38.%j 5.68 

Wari R i -2 Am, BM NIA 39.16 13.91 

Wrandab liTH.00648 Pw WA 43.93 7-23 

Yam ETH-(10650 Au E 35.60 9.05 

Yubdo (Ah) ETH-53 Asb NIA 35.M 8.86 

ZW~, Hargets ~H00657 Au NIA 38.31 14.54 

Zariga (Asb) ETHJIMSI Ah NIA 40.35 14.30 

Zelpl W&l (ClyC) -*?' clYc N/A 38.21 9.W 

Zega W&l (Coal) ETH-00660 Cam1 NIA 3813 9.89 

Ze~nbaba Woha ETH-00661 Ti NIA 39.28 5.83 

Abadida ITnvissa) I ETH-00662 I Au 1 E 1 38.88 1 5.71 

T~habe Embn ETH-00779 CII D 3831 14.20 

Agere Maryam (Ni) ETH-00791 MI NIA 38.10 5.44 

Apn Maryam (Ta) ETH-00792 Ta NIA 38.M 535 

Apero Maryam (Mo) 

E 

X-Lon 

35.65 

Y-Lat 

9.06 

ETI.I.00791 Mo N/A 38.11 5.57

I NAME 

Kanticba (Au) 

Ogaden (htr, Oas) 

IDENTLF. SUBSTANCE - CLASS x-Lon - 

Y-Lat 

ETH-0079s NtA 34.04 S,55 

ETH-00796 Gas D 43.64 5.75 

Red Sea I (ETH) ETH-00797 Pea. Gas D 41.~0 l5,OU 

Bombowlu 1 E"rH-00801 ! Kln E 1 38.73 I 6.15 

Kombelclra ETHWOR ~ ---- l n E 42.13 9.1 

Anno 'aHm TIC D 

Adigudom EEHmIO GP E 3932 l f 25 

----- 

Nesash ~-00811 M~bl NIA 39.61 1 %w 

Ham Sslm ~-00818 '3b A 39.17 1363 

S ! J = [ N ~ ) -rnaOBtg Sik MA 39.80 8.53 

EldkhD (Sib) ETH-OO%M btm WA 39.U 14 28 

- -- 

North Mi+m r -27 I A~ - r 

N~A -I 5.80 r y3

I 

~bbnyfi*rmn*~q 

(tower. 2) IrrH-ml I **r I N/* 

I~5,ll ( la,, 

Abclselo ETH-44882 Za, Pb, Cu, Au MA 34.64 10.74 

' .: . . - A 

Annex 275 :. . :. - 

... . - .. . 

:>-,.:3 

.* -,!a 

Ab- (Upper1 ETH-@#13 Au NIA' 35.39 10.70 

- 

Abumarc (River) ETH-00884 Au 

80.67 

A 34.74 

Ab- [West, East) ETHm85 A"*As' MA 34.15 10.68 

Ni. W - - 

(soh) 

A- ETH4Wl 9 N/A 38.77 9.85 

Afdm (Umk Ondofiok €lll#893 Au E 349 10.24 

Agar K ac 1 ETH-00894 Au NIA 35.48 9.5 1 

Andm I ETH- ] S~%%CI~C 1 NIA 1 3763 1 8.9% 

Ambo I ETH.00896 1 Trav I NIA 1 37.85 1 9.00 

Arm- ETH#BW Au MA 35.33 10.30 

&jo (Hurls) D W 9 8 ' Coel WA 36A7 8.93 

Arjo (Kdati) ETH-OOS~ Cd NIA 36.60 8.88 

Atp (hbo-m AleItu) 

~~~-00901 11.75 

w(hj ETH W 35.42 

Bascia ~~~-00904 Ail NIA 34.75 IO.0S 

Belm ETN- Mhl NIA 35,03 10.16

276 Mineral Resources Potential of Ethimb 

1 NAME I IDMIF- I SUBSTANCE I CLASS [ X-h I I'-b 

Belfude (Lower. Upper): 

Sirkde (Am) 

Bila 

ETH-0091 I 

ETH-009 14 

Au 

Fe 

NIA 

NIA 

34.77 

35.63 

r0.59 

9,37

NAME 1 IDENTIF. [ SUBSTANCE I CLASS I X-LO~ I Y-LU~ I 

Debre Libnos, Coal 

(Gur,S Gongit R.) 

Debre Tabor 

Dila Amuent 

Dila, 1g0 

ETH-00943 

I 

ETH-00914 

ETHd0946 

ETHd09.17 

Dila 1 ETH-00948 I Au I NIA 1 35.31 1 9.24 

Dila I ETH-00949 I Pt I NIA ] 35.35 ] 9.19 

Dilla (ClyC) I ETH-00950 I ClyC I NIA 1 35.55 1 9.45 

Dilla (Upper) 

Dura (Lower) 

ETH-0095 I 

ETH-00652 

Coal 

Kln 

Au. Pltd 

Dura Aebin ETH-00953 AII NIA 

(Lower) ETH-00954 Au NIA 

Dmi (Middle) I ETH-00955 I A I NIA 1 34.60 1 10.65 

Ebilcha (Bekuji-Motish) 

Ejoba (North) 

E~nbukneya 

Fare (Lower, Upper) ; 

Mesa ; GBbo (Middle) ; 

Oda 

Fasio (Mount) 

Gmm (Lower P) 

An 

Au 

Ao 

NIA 

NlA 

MIA 

NIA 

N/A 

NIA 

ETH-00956 Au NIA 

ETH-00957 AU NIA 

ETH-Om58 AU NtA 

ETH-00959 Au NIA 

-- 

ETH-OW60 MO 

ETH-00961 Au N/A 

Gaza~~(Middle, Upper) I ETH-00964 I Au I N/A 

Geb (Middle) 

38.82 

38.01 

35.41 

35.24 

35.39 

35.47 

9.73 

1 1.83 

I I r I I 

1NIA ] 34.80 10.64 

Gih (Uppar) 

Gomi (Amuent), Gomi 

(her) 

Gotni (Head Waters), Roro, 

G~liso (North) 

ETH-00969 

ETH-00970 

ETH-0097 1 

AII 

Au 

Au 

NIA 

NIA 

MIA 

34.87 

35.44 

35,48 

6.23 

9.28 

9.38 

10.15 

10.58 

9.13 

9,18 - 

ETH-00973 LstC NIA 37,75 8.97


Mendi (Gerba) 

Mendi (KoII~) 

Menp (Upper, Middle) 

Milendu (Belkwcl) 

ETH-01001 

ETH-0 1002 Coal NIA 34.98 

----- 

ETH-01003 

Au NIA 34,75 

FTH-01004 

Coal 

Mrbl 

NIA 

NIA 

35.09 

35.14 

9.72 

9.81 

10.37 

10.33

NAME SUBSANCE CLASS 

*(-) FCH-01029 

Sirkoltpled Wllrcrs), 

Sirkole (Lower) ; Tuma- 

ETHQlOM 34.52 10.23 

Sirkd~ Junction; Tuma mM)1031 MA 34.77 10.62

280 Minerd Remmxs Potential of Ethiopia 

Tsoli (SW) 

Tdi (West) 

Tsoli. 

NAME 

Twli, G ha (Upper) 

Tulu Boli I ETH911W I ah I NIA I 11.39 I 9.51 

TUIII Di~ntu EM41011 Ni, Co, Cr, R 

TuluHasi (SW) ETHDIO12 Mo 

Tuner (Lw) 

fTH41038 

ETH-01039 

Twncl (Uppm) FM41W Au 

T-t IUpw) FM.01045 AII 

Turn, Hdm, De~nba 

Ube (Wube) 

wowu 

aceem WWr) 

Weka (Gran) 

Mai Dao 

Axam 

Mua(h) 

IDENTIF. 

TKO1036 

EW1037 

ETH41086 

ETH+1047 

-- 

ETH-01055 

ETH-01056 

SUBSTANCE 

Cu 

CII 

FC 

All 

Am 

Mo 

.- 

Au 

Gran 

CLASS 

NIA 

A 

NIA 

A 

WA 

NIA 

X-h 

35.05 

35.06 

33.08 

35.09 

34.79 

34.69 

Y-LPt 

10.23 

10.28 

10.28 

103 

I I 

NIA 35.25 10.06 

NIA 

NIA 

38.01 

38.82 

ETH4IOW Mtbl D 3838 

----- 

ETH41061 Amt PUA 38.72 

ETH41062 Amt NIA 38.90 

10.09 

10.59 

1 1.83 

6.05 

14.30 

14.13 

14.17 

: '

285 

Annex 4. Techniques utkd in digitizing the geology and 

mineral map of Ethiopia 

The folIowing are the steps involved in developing the digital 

database for Geology and mined map of Ethiopia. 

Data input 

k-,., . . 

thiopia was first scanned to derive a raster 

56 cohurs in TIF format 

the project projection that will serve as a base for all 

works were performed using Mercator 

Projection-Datum NAM7-Ellipsoid Clarke 1 866; 

Ektracting contour lines, Political boundaries and drainage 

from DC W (Digital Chart of the Worid) were performed. 

Microstation and MS Geocoordinator, grids were cteated in 

ect all vector data (topographic, drainage, 

and boundaries data) onto the he. 

ion DescarW, gemeferencing raster geological 

map to the Mercator base cartographic map with grid and 

hic data were done. 

d labeis edited under Microstation using a 

on: hydrographic data (blue), politid 

boundaries (black) c) grid (magenta) on transpent suppo 

ew grid on paper; 

and an WP Plotter (HP25OO). printing raste 

i mapat1:2,000,000scale, 

:

286 Miml Resources Potential of Ethiopia 

Adding informatiori and apgmdhg: 

Hand, drawing (in black) was performed to simpli@ the 

geology on transparent output (by matching the hydrographic 

network and grid between the two supports). Drawing the 

geological contacts, faujts, symbols and placing a label point 

for each geological unit was done; 

Scanning the drawing (in binary) to remove hydrographic and 

grids (blue and magenta); 

Under MicroStatioa, I/RASB and IIGEOVEC, gareferencing 

the raster data; md interactive vectorizing the geological 

boundaries (one layer for each object category: contact, fault, 

etc.) was perfumed; 

Placing interactively the label points and transferring the data 

to ArcInfo (twundaries and label points) was done. 

Final editing and preparing layouts far printing 

With Archfo, generating the polygon topology; batch pmcess 

to were. performed to calculate the intersectioris between the 

line network and creates the polygons (by chaining the lines 

around each label points); 

Detects the errors (polygons without label and polygons with 

dmnt lakls). 

If there are errors 

Importing the errors in Microstation for correcting running 

&Info process until all the errors are corrected. 

When aU the errors are corrected 

Under Microstation, imparting the polygons created with 

ArcInfo. Function the label points, the polygons may be fill4 

with a colour andlor a pattern); a specific colour chart has been 

E#l! defined for the Africa R&D project; 

Under Excel, creating the le&nd;

g faults, titles, logos,). At this stage, the 

~cgeological 

map was finalid. 

. Mineral resources data 

Scanning all available documents of Ethiopia (black and 

white) on AN ATECH scanner {with grey level); 

Under Microstation Descartes, georeferencing (warping) 

raster data in Mercator with grid and topographic data; 

Under MapInfo, calculating the coordinates (longitude and 

I latitude) for, each occurrence and transferring the results in 

I 

Updating of the data by introducing in the database, 

complementary information extracted from recent publications 

and b m economic journals; 

Under MicroStation, creating the legend for minds. At this 

stage, the synthetic digital mineral map was finalia, 

3 

Under Microstation, printing the map was done using HP 

plotter (HP25OO). Kg;. 

3q.:' 

, (6:' 

b .,, , ' 

. :.? 

.,. 'A'


3. CD-ROM ,t . - 

8, - 

.;A:, 

* Tmfmhg_the- 

data to MapInfo (layers: topography, geology, 

hults, symbols and mineral deposits) h m Microstation; 

Under Descartes, creating the map viewer from the geological' ' 

and minerd map; 

Creating CD-ROM (using HP CD Writer Plus 7200). 

4. Software used 

The following software was used to make the digital database of 

the map: 

Microstation (editing vector data); 

Descartes (editing raster data, colour and blackhvhite); 

Micros tation geocoordinator (used to manage projection 

systems). 

Infergraph software (which runs on MicroStation) 

I/MSI3 (editing raster data, only blacklwhite); 

UGEOVEC (interactive vectorizin~transfom raster to vector); 

ESRI software; 

ArcInfo (CIS); 

AD.D.E software, 

MapInfo (GIs). 

ANATECH Software 

Scansmith scan and Scansmi* view 9 to wan @ visualize 

the raster.

Fa, -w 

0: Annex 2g9 

Annex 5. Mining law and invwtment opportunities in Ethiopia 

Policy 

The economic policy of Ethiopia envisages the need for the 

participation of national as well as international investors in 

different economic sectors including mining. The government 

realizing the unique nature of mining activities and to encourage 

investem in area opted to regulate the mining activities through 

laws specifically applying to mining as opposed to other areas of 

investment being regulated by the investment laws. 

Inveatmea t opportunities 

The country is endowed with a variety of mineral resources. All 

interested pasons and groups are invited to invest in the mining 

industry of Ethiopia. 

The Federal Republic of Ethiopia issued a new Mining 

Pmla~nation and Mining Tax Proclamation in June 1993. These 

laws are the outcome of vigorous research in the field of mining 

investment. They replace Mining Proclamation No, 282 of 1971 

which governed mining activity in Ethiopia for the last 22 years. 

The main objective of the new mining law is to improve the 

legal framework for mining investment in the country. Realization 

of the shortcomings of earlier laws and policies was very important 

in taking the subsequent corrective measures. The future of the 

mining sector is now firmly allied to private investment. The 

: preamble to the new mining law states that the law recognizes the 

significant role of private investment in capital formation, ! 

technology acquisition and wketing of minds. The Mining 

Tax Proclamition No.. 53/1993 is legislation complementary to the 

i 

Mining Proclamation. The Tax Proclamation fully recognizes the 

high risk nature of mining investment and provides a liberal reward 

I 

for those who venture into the sector. This can be demonstrated 

from the following benefits stipulated in the law: 1 

1 

1 

i I 

I 

I I

I exploration 

ZBO Mind Resources Potential of Ethioaia 

- 35% tax on taxable income generated from mining 

operation; 

- 10% dividend tax; 

- 2% optional state free equity; 

- Ten year losses carry fbmd; 

- Generous deductions and calculations of expenditure; 

- Reinvestment deduction; 

- Right to sell the produced minerals locally or abroad 

without obtaining other licenses; 

- Exemption from customs duties and taxes on equipment, 

machinery, vehicles except Seda cars and spare parts 

necessary for mineral operations; 

- Provide for dispute settlement through negotiation and 

international arbitration; 

- Write off of investment within four consecutive years; 

- Low royalty and tax rate; 

- Fair exchange control arrangements, with no restrictions 

on repatriation of profits and dividends in the currency of 

investment or in an approved currency; 

- The right to hold a foreign currency account in Ethiopia; 

- The right to dispose of the- produced minerals locally or 

abroad without obtaining other licences; 

- require environmental impact study. 

The calcuIations for det,mination of taxable income are 

devised so that the investor will get .a fair reward for his effort and 

investment in finding and producing the minerals. 

The Mind Operations Department of the Ministry of 

Mihes is the focal point to receive, facilitate and process 

and mining applications presentd by foreign 

company's joint venture with local companies and.sdl to large 

sale mining activities to be carried out by l d companies.

Mineral Resources Potential - Geothermal Resources

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