Ikeshiro Mine
Ikeshiro, Matsuzaki city, Kamo county, Shizuoka pref., Japan
"No Trespassing" sign was erected.
Occurrence
Manganese oxide deposit formed by low temperature, strong alkaline metasomatism of andesitic tuff of the late Miocene (7.0 Ma) Shirahama Formation. The sedimentary circumstance of the host andesitic tuff is shallow marine in a warm climate as Lepidocyclina fossils are observed in the deposit. The hydrothermal activity may be ralated to the middle Pleistocene (62 ka) Chokuro Volcano, source of the andesite lava unconformably overlies the Shirahama Formation in this locality. Ages of sediments were determined by microfossils, and volcanic rocks by K-Ar radiometric dating.
Reported Minerals
- Todorokite
- Pyrolusite
- Sepiolite
Mineral Assemblages
- Todorokite - Pyrolusite - Sepiolite
Localities
- Tabi (Metasomatism, Braunite)
- Ikeshiro Mine (Metasomatism, Todorokite)
- Cape Osaki (Basalt lava, Ranciéite)