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Tensho Mine

Toi, Izu city, Shizuoka pref., Japan


Tensho Gold Mine


Hydrothermal Au-Ag deposit

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.

Tensho Mine

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


  • 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.
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