Natural Science in Archaeology

170 7 Metals and Related Minerals and Ores
Red ochre has been used for decoration at least since Mousterian times
(in France). It was used in the Upper Paleolithic in cave painting and since the
Neolithic for painted pottery. Recent excavations in south-central Sicily recovered
small jars of ochre from the first phase of the local Copper Age (Maniscalco 1989).
Maniscalco believes this discovery provides evidence of contact between Sicily
and Malta, where potters used ochre that may have been imported from Sicily. Red
and yellow ochres used by aboriginal societies in southern and western Australia
were found to have a diverse mineralogy, being mixtures of up to seven minerals
(hematite, ankerite, calcite, dolomite, quartz, feldspar, and corundum) (Jercher
et al. 1998).
Goethite/limonite, α-FeO(OH), has a hardness of 5.0–5.5 and a density range
of 3.3–4.3. The name goethite is in honor of Goethe, the German poet. Goethite
is a major ore of iron in some locations. Limonite is essentially a field term used
by geologists for hydrous iron oxides of uncertain identity but largely goethite.
Goethite is one of the most common and most widespread of minerals. It typically
forms as a weathering product of iron-bearing minerals. Goethite is the gossan or
“iron hat” that caps oxidized sulfide deposits. Goethite is common in near-surface
sediments and soils as a secondary or concretionary material precipitated from circulating
groundwater. The dearth of archaeological knowledge concerning iron ore
mines of the European Iron Age probably stems from the wide occurrence of small,
shallow deposits of limonitic and hematitic iron ores. The exploitation of such ores
would have had little lasting effect on the landscape.
At the Nichoria excavation in southwestern Greece, goethite was found as small
rod-shaped forms in Bronze Age contexts. This initially created quite a stir, because
it was conjectured that these might have been pre-Iron Age oxidized iron nails.
However, I found the rods to have a radial cross-sectional structure similar to other
known goethite nodules rather than the concentric or structureless cross-section that
would be consistent with a rusted metallic iron nail.
When yellow in color, goethite is called yellow ochre. Many yellow ochres
also contain jarosite [KFe (SO ) (OH) ] or natrojarosite [NaFe (SO ) (OH) ]. Sev-
3 4 2 6 3 4 2 6
eral types of ochre fragments were recovered from the Natufian layers of el-Wad
Cave, Mount Carmel, Israel. Yellow ochre was available from local deposits and
was apparently used to produce a red hematitic pigment, residues of which were
found on basalt pestles in the cave (Weinstein-Evron and Ilani 1994). This would
have required heating the goethite [FeO(OH)] of yellow ochre to convert it to red
hematite (Fe O ). 2 3
Magnetite, Fe2+ 3+ Fe O4 , has a hardness of 5.5–6.5 and a density of 5.18. It is
2
iron-black with a metallic luster and a black streak. It is magnetic enough to act as a
natural magnet known as lodestone. It is common in small amounts in most igneous
rocks, and is occasionally sufficiently concentrated in lode or placer deposits to be
classed as an ore deposit. An early form of steel was made in India by reducing a
mixture of powdered magnetite and hematite in small crucibles with wood or green
leaves as a carburizer and with a calcareous flux (Hulme 1940).
The Latin name for lodestone was adamas, which was also the name given to the
compass in the time of Edward III of England. A wide-ranging history of lodestone,