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Itaga Mine

Itaga, Kanuma city, Tochigi pref., Japan


Mori Mine


Pneumatolytic deposit

W pneumatolytic deposit associated with the early Paleocene (63 Ma) Karasawa Granodiorite intruded in the Late Jurassic (145 Ma) Kurohone-Kiryu Unit. The Karasawa granodiorite is S-type (Ilmenite-series). The Kurohone-Kiryu Unit corresponds to the Kanayama Unit of the Tamba-Mino-Ashio accretionary complex. Ages of sedimentary rocks were determined by radiolarians, and granodiorite by K-Ar radiometric dating of muscovite and biotite.

Itaga Mine

Outcrop of andalusite-bearing quartz vein in the Karasawa Granodiorite. The pink part at the left of the scale coin is the andalusite-rich quartz vein associated with colorless fluorite, topaz, and muscovite. The wall rock at the top of this photograph is brown granodiorite altered by weathering.

Reported Minerals

  • Copper
  • Fluorite
  • Corundum
  • Goethite
  • Molybdenite
  • Lollingite
  • Chalcopyrite
  • Ferberite
  • Andalusite
  • Topaz
  • Jarosite
  • Scorodite
  • Schorl

Mineral Assemblages

  • Quartz - Andalusite - Muscovite - Corundum - Fluorite - Topaz
  • Quartz - Lollingite - Ferberite
  • Quartz - Molybdenite
  • Quartz - Schorl


  • around 1900: Explored for Au-Ag and Cu.
  • 1939: Granodiorite-hosted W deposit was discovered.
  • 1940-1945: W was open-pit mined during World War II.
  • 1952: Hornfels-hosted W deposit was discovered, and mined.
  • 1961: Closed. Produced 23.5 ton W concentrates.
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