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Ogibira Mine

Osa-Kominami, Niimi city, Okayama pref., Japan


Moderate-T hydrothermal skarn deposit

Skarn formed by the Late Cretaceous (70 Ma) granite intruded in the Permian Guadalupian (270 Ma) Akiyoshi accretionary complex. There is an oxidation zone of the moderate temperature hydrothermal deposit associated with the skarn. The granite is I-type (Magnetite-series), and is approximately 2 km apart from this locality. The limestone is the Carboniferous Early Mississippian to Permian (350-270 Ma) reef limestone. Ages of sedimentary rocks were determined by radiolarians, limestone by microfossil, and granite by K-Ar radiometric dating. The 2nd locality for Köttigite.

hgihira Mine

Outcrop of oxidation zone of the skarn deposit in the Akiyoshi accretionary complex. The fragile yellowish-gray part at the upper side of the scale coin is a pyrite-arsenopyrite vein. The surface of this outcrop is covered with a brown crust of limonite. Limonite was formed by oxidation of Fe-bearing minerals in the pyrite-arsenopyrite vein. Various arsenate minerals were recovered from open spaces of the limonite. The origin of As in these arsenate minerals is that in arsenopyrite.

Reported Minerals

  • Legrandite
  • Köttigite(Kottigite)
  • Smithsonite
  • Pharmacosiderite
  • Hemimorphite
  • Scorodite
  • Aurichalcite
  • Hydrozincite
  • Brochantite
  • Malachite
  • Aragonite
  • Chabazite
  • Hedenbergite

Mineral Assemblages

  • Limonite - Legrandite - Kottigite
  • Hedenbergite - Calcite


  • 1953: Closed. This mine had been produced copper.
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