Narayama
Hirotani, Aga city, Higashi-Kambara county, Niigata pref., Japan
Occurrence
Intermediate acidic metasomatic rocks of low-T silicified zone
Silicified rhyolite, rhyolitic pyroclastics, and rhyolitic tuff of the Fukutori Green Tuff Member in the middle Miocene (15 Ma) Tsugawa Formation. The Tsugawa Formation is marine sediments formed under the warm current. The Tsugawa Formation unconformably overlies Mesozoic granite and the Early Miocene Mikawa Formation. Ages of the Tsugawa Formation were determined by microfossils.
Outcrop of rhyolitic tuff breccia of the Fukutori Green Tuff Member, Tsugawa Formation. The rhyolitic tuff breccia is composed of rhyolitic lapilli, rhyolite blocks, perlite, and chalcedony. The green block at the left of the coin is chalcedony. The red lapilli is hematite-rich rhyolite and chalcedony. The surrounding fragil white matrix is rhyolitic tuff. This chalcedony looks green as it contains fine crystals of aluminoceladonite.
Reported Minerals
- Chalcedony
- Ferrierite-K
- Aluminoceladonite
Mineral Assemblages
- Chalcedony(Gangue) - Ferrierite-K
- Quartz - Aluminoceladonite
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)