An overview of vis-nir-swir field spectroscopy - Spectral International

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Core Logging
Spectral core logging is one of the major applications of reflectance
spectroscopy. Figure 18 presents a spectral core log..
HIGH SULFIDATION SYSTEM DRILL HOLE :: GOLD vs MINERALOGY
DEPTH Wave Au Kl Dik Alk Ill Sm Sil Jar Ch ALT Minerals
40 2206 0.005 x x 1 Jarosite, trace gyp, illite?
68 2206 0.005 x x 1 Illite + silica
74 2206 0.009 tr x x 1 Illite, silica tr gyp tr kaolinite
80 2206 0.024 x x x 1 Illite -> kaolinite, gyp, silica
81 2204 0.024 x x 1 Illite, gypsum - - jarosite?
94 2210 0.007 x 1 Illite
100a 2206 0.013 x x 1 Illite, jarosite
117 2206 0.008 x 1 Illite
124 2204 0.025 x x 1 Illite jarosite
140 2212 0.005 x x 1 Illite, jarosite, gypsum?
146 2192 0.011 x x 1 Illite, silica
150 2164 0.011 x 1 Kaolinite
164 2166 0.099 x 1 Kaolinite, well x/n
170 2168 0.099 x 1 Kaolinite, MW
173 2180 1.473 x x x 4 Dickite, alunite, kaolinite
175 2180 1.473 x x 4 Alunite + dickite
178 2170 1.473 x x 5 Alunite + silica
181 2177 0.133 x x x 4 Dickite and alunite silica
182 2181 0.133 x tr 3 Dickite, trace alunite
183 2180 0.133 x 3 Dickite
186 2166 0.035 x 1 Best kaolinite
196 2167 0.013 x x 1 Kaolinite + silica
204 2167 0.005 x 1 Kaolinite
214 2177 0.099 x tr 1 Kaolinite tr dickite
218 2166 0.099 x x 1 Kaolinite - poor illite
224 2166 0.016 tr x 1 Smectite + minor kaolinite
229 2167 0.016 x 1 Kaolinite
235 2164 0.196 x 1 Kaolinite - still wet
238 2164 0.196 x 1 Kaolinite
244 2164 0.007 x 1 Kaolinite
Pit Bench Mapping - Blast Holes
Considerable information can be gained through the analysis of blast holes in an
open pit mine. Although blast holes are assayed, in-situ mineralogical analysis
can provide alteration types, which if spectrally defined, will give the metallurgist
information needed for efficient mill recovery or heap leach pad blending.
17
A
B
C
D
E
F
Figure 18 - An Excel chart
that shows mineralogy
against alteration type
against gold assay values.
Plotting the minerals in this
way gives an excellent
comparison of the
presence of gold related to
mineralogy. The alteration
classifications are
indigenous to the high
sulfidation system and
represent mineral
associations.
Figure 19 - This plot is a compilation of
different alteration types from a copper
mine, defined using spectroscopy.
These include [A] muscovite, [B]
weathered muscovite shown by large
water feature, [C] illite with very minor
kaolinite overprint, [D] illite - kaolinite
mixture, [E] kaolinite – illite mixture, [F]
kaolinite. By matching metallurgical
data to the clay type, it was possible to
determine that too much kaolinite
would cause recovery losses.