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

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Potassic - K-silicate
This alteration occurs in the core of porphyry systems, particularly when hosted
by felsic intrusions - granodiorite, quartz monzonite,granite, seyenite. Minerals
include K-feldspar, quartz, albite, muscovite, anhydrite, epidote. Feldspars do
not have detectable bonds in the SWIR region and therefore their profiles do not
have distinctive features.
Sodic, Sodic-Calcic
Occurs with minor mineralization in the deeper parts of some porphyry systems
and is a host to mineralization in porphyry deposits associated with alkaline
intrusions.
albite, actinolite, diopside, quartz, magnetite, titanite, chlorite, epidote , scapolite
Figure 37 - Sodic- Calcic alteration plots
Albite, actinolite, Fe-chlorite, epidote,
Mg-chlorite, marialite, mizzonite,
diopside, quartz, magnetite.
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Figure 38 - Phyllic alteration includes:
Illite, muscovite, iron chlorite, Mgchlorite,
gypsum, anhydrite, quartz,
pyrite.