Shibusawa Mine
Shibusawa, Hadano city, Kanagawa pref., Japan
Occurrence
Intermediate acidic metasomatic rocks of low-T silicified zone
Smectitization deposit formed by hydrothermal alteration of tuff in the middle Miocene (15 Ma) Oyama Subgroup, the Tanzawa Group. The Oyama Subgroup is mainly composed of basaltic to andesitc lava and pyroclastics. The Tanzawa Group is considered as the accreted Izu island arc. Gypsum and pyrite was formed in the alteration zone. Ages of sedimentary rocks were determined by microfossiles.
Outcrop of tuff of the Oyama Subgroup, Tanzawa Group subjected to smectitization alteration. The grayish-green block is altered tuff, and is hard as it was silicified. White soft parts around them are clay rich zones. Fine yellow pyrite crystals are included everywhere in this outcrop. Reddish parts are abundant in fine crystals of rutile.
Reported Minerals
- Gypsum
- Pyrite
- Rutile
- Beta quartz
Mineral Assemblages
- Gypsum - Pyrite
- Quartz - Rutile
History
- 1935: Began to mine gypsum and pyrite.
- 1948: The mine was closed.
Localities
- Narayama (Rhyolite, Ferrierite-K)
- Katsura Island (Rhyolite, Ferrierite-Mg)
- Kita-Tomida (Dacite, Chalcedony)
- Shibusawa Mine (Gypsum deposit)
- Nanataki fall (Pyrite)
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)