Minamiite-Alunite zone
Chemical Process (Alteration) - Open system under ground (Acidic metasomatism)
Synonym
High temperature subzone of Kaolinite zone, Alunite zone (Middle temperature), Argillized zone (Dickite, Nacrite)
Index Minerals
Natroalunite-2c (Minamiite)
Required Geological Setting
Occurrence
Metasomatic zone formed by acidic hydrothermal fluid of 220-250 degree associated with Rhyolitic magma activities. This alteration is a part of alunitization and argillization. Protoliths are felsic rocks. Minamiite-Alunite zone may be associated with Moderate-T hydrothermal deposits.
Distribution of Minamiite-Alunite zones described in this site. Yellow lines are volcanic fronts.
Change of mineral assemblages
- [ Extinct ] Kaolinite, Smectite/Illite, Smectite/Chlorite, Gypsum
- [ Appear ] Natroalunite-2c (Minamiite), Dickite, Nacrite, Rutile, Illite, Chlorite
Mineral Assemblages
- Alunite, Natroalunite-2c (Minamiite), Quartz, Pyrite, Dickite, Nacrite, Rutile, Illite, Chlorite, (Anhydrite, Diaspore, Zunyite, Topaz)
Localities
- Sessho creek (Vein type)
- Funabara mountain pass (Replaced type)
- Ukusu Mine (Replaced type)
Related Occurrences
- Halloysite zone (Alunite zone, Argillized zone)
- Kaolinite zone (Alunite zone, Argillized zone)
- Minamiite-Alunite zone (Alunite zone)
- Pyrophyllite zone
- Smectite zone (Argillized zone)
- Interstratified mineral zone (Argillized zone)
- Illite-Chlorite zone (Propylite zone)
- Epidote-Actinolite zone
- Stilbite-Mordenite zone (Zeolite zone)
- Heulandite-Analcime zone (Zeolite zone)
- Laumontite-Albite zone (Zeolite z., Propylite z.)
- Wairakite-Albite zone (Zeolite zone)