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Halloysite zone

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


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

Index Minerals


Required Geological Setting

Metasomatic rocks (Acidic)


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)


Related Occurrences

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