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Honzawa Mine

Magi, Otsuki city, Yamanashi pref., Japan


Hydrotherma Au-Bi-Te deposit

Au-Bi-Te-bearing low temperature hydrothermal deposit at the boundary between the late Miocene (10 Ma) Tokuwa Granite and the middle Eocene (45 Ma) Gongenyama Unit of the Sagamiko Group, a member of the Shimanto accretionary complex. Granite at this locality is the S-type (Ilmenite-series) margin of the I-type (Magnetite-series) Tokuwa Granite. The S-type (Ilmenite-series) margin was formed by reduction reation of granite magma with surrounding pelitic rocks. The Gongenyama Unit at this locality has been subjected to Albite-Epidote-hornfels contact metamorphism. Ages of sedimentary rocks were determined by radiolarians, and granite age by K-Ar radiometric dating of biotite and whole rock.

Honzawa Mine

Au-bearing quartz vein in shale of the Gongenyama Unit subjected to contact metamorphism by granite. The light gray part at the upper left is metamorphosed shale. The scale coin is on the milky white quartz vein. Au-Bi-Te minerals are in this quartz vein.

Reported Minerals

  • Gold
  • Sulphur
  • Bismuth
  • Joséite(Joseite)
  • Bismuthinite
  • Pyrite
  • Arsenopyrite
  • Ilmenite
  • Bismutite
  • Scorodite
  • Chabazite

Mineral Assemblages

  • Quartz(Gangue) - Joséite(Joseite) - Gold - Bismuthinite - Bismutite
  • Quartz(Gangue) - Pyrite
  • Quartz(Gangue) - Arsenopyrite - Scorodite
  • Granite(Host) - Chabazite

Produced metal(1942-1943)

  • Gold ore: 16 tons


  • 1942: Began to mine at the open pit.
  • 1943: Closed.
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