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Shizugi Mine

Yamada, Hagi city, Yamaguchi pref., Japan


Aobase Mine


Moderately high-T hydrothermal deposit

Marine oxidation zone of moderate temperature hydrothermal deposit in the Late Cretaceous (90 Ma) granite intruded in the Early Cretaceous (105 Ma) Shimonoseki Subgroup of the Kanmon Group. The Kanmon Group is fresh water sediments, and the granite is S-type (Ilmenite-series). Approximately 15 km apart from the Late Cretaceous (88 Ma) Sasanami Caldera Complex. Ages of sedimentary rocks were determined by K-Ar radiometric dating of hornblende and fission track dating of zircon, caldera complex by Rb-Sr whole rock isochron age.

Shizuki Mine

Outcrop of oxidation zone of moderate temperature hydrothermal deposit. The green crust on the surface is atacamite. The white basement under the atacamite crust is granite. The origin of Cl in atacamite is probably seawater.

Reported Minerals

  • Atacamite
  • Chalcopyrite
  • Arsenopyrite
  • Pyrite

Mineral Assemblages

  • Atacamite


  • 1947-1949: Mined 350 t ore of Cu 9 %.
  • around 1960: The mine was closed.
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