Early Argillic to Advanced Argillic Alteration
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Alunite
Fine-grained lacustrine tuffs replaced by alunite: hot spring?
KAl3(SO4)2(OH)6
Jarosite, Illite, Smectite & Montmorillonite
Intense, white altered rock, original host possible feldspar porphyry as suggested by the rectangular cavities of former feldspar phenocrysts
Illite, Smectite, Gypsum, Nacrite & Vermiculite
White chalky rock, no obvious original texture noted (hosted in andesite\dacite feldspar porphyry)
Montmorillonite, Iron Smectite & Iron Saponite
Intense, white altered rock, original host possible feldspar porphyry as suggested by the rectangular cavities of former feldspar phenocrysts
Illite, smectite, dickite, nacrite, sepiolite, Gypsum & Palygorskite
White chalky rock, no obvious original texture noted (hosted in andesite\dacite feldspar porphyry
Chabazite Group, Dickite, Beidellite & Barite
Strong argillic altered rock. Small rectilinear casts, now finely crystalline-aligned, may be relict feldspars
Dickite, Alunite, Kaolinite & Muscovite (Sericite)
White chalky rock, no obvious original texture noted (hosted in andesite\dacite feldspar porphyry
K-Alunite
Altered feldspar porphyry breccia (fault?) cemented and replaced by alunite bladed crystals evident on one weathered surface
Alunite & Quartz
Alunite & Jarosite
Brecciated altered tuff\siltstone? cemented by alunite
Alunite, Jarosite, Palygorskite & Quartz
“vuggy” alunite + silica: original rock totally altered, presence of small quartz shards suggests felsite ash tuff origin
Quartz
“vuggy” quartz
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