Tensho Mine
Toi, Izu city, Shizuoka pref., Japan
Synonym
Tensho Gold Mine
Occurrence
Low temperature hydrothermal Au-Ag deposit in andesitic and basaltic pyroclastic rocks of the late Miocene (7.5 Ma) Yugashima Group. The pyroclastic rocks, the host of the deposit, is calc-alkaline to tholeiitic, and have been subjected to strong prppylitization alteration. The Yugashima Group unconformably underlies the Shirahama Group. Ages of volcanic rocks were determined by K-Ar radiometric dating and fission track dating of zircon.
Outcrop of andesitic tuff of the Yugashima group associated with the Au-bearing quartz veins. The vertical white veins are Au-bearing quartz veins. The light gray host is propylitized andesitic tuff.
Reported Minerals
- Gold bearing quartz
- Adularia
- Silver
- Acanthite?
Mineral Assemblages
- Quartz(Gangue) - Adularia - Gold
- Quartz(gangue) - Acanthite? - Silver
History
- 750's: Gold nuggets were mined in the placer deposit.
- 1577: Started to mine under the name of Tensho Mine.
- 1625: Tensho Mine was closed.
- 1854: Buried in the ground by the Ansei-Tokai Earthquake.
Localities
- Shobusawa (Izu Peninsula)
- Seikoshi Mine (Izu Peninsula)
- Toi Mine (Izu Peninsula)
- Tensho Mine (Izu Peninsula)
- Takatama Mine (Gold/Silver deposit)
- Nishizawa Mine (silver sulfides)
- Nebasawa Mine (Gold/Silver deposit)
- Hishikari Mine (Kyusyu Island)