Shin-yo Mine
Soehi, Sanada village, Ueda city, Nagano pref., Japan
Occurrence
Acidic metasomatic rocks of Pyrophyllite zone
Pyrophyllite deposit formed by hydrothermal alteration by the late Miocene (9 Ma) Tenguiwa Dacite Dike of andesitic-dacitic tuff and dacite of the Fujiyama Member in the early Miocene (17 Ma) Uchiyama Formation. The Tenguiwa Dacite Dike is associated with the Sugadaira Quartz Diorite. The Tenguiwa Dacite Dike and the Sugadaira Quartz Diorite is I-type (Magnetite-series). Less than 100 m apart from the Tenguiwa Dacite Dike, the heat source. Ages of sedimentary rocks were determined by microfossils, quartz diorite and dacite by K-Ar radiometric dating of whole rock.
Outcrop of dacitic tuff of the Fujiyama Member, Uchiyama Formation subjected to pyrophyllitization alteration. The outcrop is composed of fine pyrophyllite and quartz. There are many small cavities. The brown parts are dirt by limonite.
Reported Minerals
- Zunyite
- Pyrophyllite
- Pyrite
- Corundum
- Barite
Mineral Assemblages
- Pyrophyllite - Zunyite - Limonite
- Phyrophyllite - Corundum
Localities
- Momura (B rich)
- Kyonosawa (B rich)
- Shima Mine (B rich)
- Hinomaru-Nako Mine (P rich)
- Yoji Mine (Al,F rich)
- Shin-yo Mine (Al,F rich)
- Mount Kawate (Zunyite)
- Mount Shoko (Al rich)
- Nekoyama (Al rich)
- Mitsuishi (Al rich)
- Isshiki Mine (Al rich)
- Toho Mine (Al rich)
- Hongo Mine (Sulfide deposit)
- Masutomi Mine (Sulfide deposit)
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)