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Halloysite zone

Chemical Process (Alteration) - Open system under ground (Acidic metasomatism)

Synonym

Alunite zone (Low temperature), Argillized zone (Halloysite)

Index Minerals

Halloysite

Required Geological Setting

Metasomatic rocks (Acidic)

Occurrence

Metasomatic zone formed by acidic hydrothermal fluid of 50-100 degree associated with Rhyolitic magma activities. This alteration is called halloysitization and is a part of alunitization or argillization. Protoliths are felsic rocks. Halloysite zone may be associated with Hydrothermal Au-Ag deposits or Hot spring deposits.

Halloysite zone

Distribution of Halloysite zones described in this site. Yellow lines are volcanic fronts.

Change of mineral assemblages

  • [ Appear ] Alunite, Halloysite, Pyrite

Mineral Assemblages

  • Alunite, Halloysite, Cristobalite, Pyrite, Smectite, (Gypsum)

Localities

Related Occurrences

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