Nishinomaki Mine
Minami-Nomaki, Shimonita city, Kanra county, Gunma pref., Japan
This locality is closed to collecting.
Synonym
Saimoku Mine
Occurrence
Low-T hydrothermal deposit associated with the late Miocene (6.0 Ma) andeste-dacite dikes intruded in andesitic tuff breccia of the Motojuku Formation of the same age. The Motojuku Formation is composed of andesitic tuff breccia and andesitic-dacitic dikes filling the late Miocene-Pliocene Motojuku Caldera. Approximately 1 km apart from the Ichinokaya Caldera Complex, the caldera complex of the Motojuku caldera. Ages of volcanic rocks were determined by K-Ar radiometric dating.
Outcrop of realgar veins in andesitic tuff breccia of the Motojuku Formation. The grayish-white host is altered andesitic tuff breccia. The red to orange parts are realgar. Fine realgar grains are scattered in the host.
Reported Minerals
- Realgar
- Orpiment
- Wakabayashilite
- Pyrite
- Marcasite
- Tennantite
- Senarmontite
- Stibiconite
- Barite
- Stibnite
Mineral Assemblages
- Realgar - Pyrite - Stibnite
- Realgar - Orpiment - Quartz - Wakabayashilite
Localities
- Nishinomaki Mine (Andesite, Realgar)
- Akadani Mine (Rhyolite, Stibnite)
- Furue (Rhyolite, Realgar)