Myoho Mine
Shimobe, Minobu city, Minami-Koma county, Yamanashi pref., Japan
Occurrence
Sediment-hosted copper deposit (Shallow-marine)
Sulfides such as chalcocite and djurleite are disseminated in the middle Miocene (14 Ma) Kanzaka mudstone member at the bottom of the Ichinose formation, Nishi-Yatsushiro group. Basalt and andesite of the Nishi-Yatsushiro group are tholeiitic or alkaline. Secondary minerals of Cu are formed with zeolite by Prehnite-Pumpellyite facies regional metamorphism. The Nishi-Yatsushiro group can be interpreted as sediments at the back-arc basin of the old Izu-Ogasawara arc. Ages of sedimentary rocks were determined by radiolarians.
Outcrop of the oxidation zone of a sediment-hosted Cu deposit in mudstone of the Kanzaka mudstone member, Ichinose formation. Cu-bearing minerals were scattered in brown mudstone. The surface of this outcrop exhibits the onion structure by weathering. The green parts are composed of malachite and brochantite.
Reported Minerals
- Chalcocite
- Djurleite
- Bornite
- Calcite
- Barite
- Devilline
- Brochantite
- Malachite
- Chrysocolla
- Allophane-Cu
- Laumontite
- Stilbite
- Heulandit
- Ice/Water
Mineral Assemblages
- Chalcocite - Djurleite
Localities
- Myoho Mine (Mudstone)
- Sawaguchi Mine (Sandy mudstone)
- Rammelsberg Mine (Devonian Shale)