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Hirasawa Mine

Enzan-Hirasawa, Koshu city, Yamanashi pref., Japan

This locality is closed to collecting.


Titanium type rare-element pegmatite

Alpine fissure in the late Miocene (10 Ma) Tokuwa Granite. Granite at this locality is ilmenite-series margin of the I-type and magnetite-series Tokuwa Granite. The ilmenite-series margin was formed by reduction reation of granite magma with surrounding pelitic rocks. The pelitic rock near this locality is shale of the Shimanto accretionary complex, probably the middle Eocene (45 Ma) Gongenyama Unit of the Sagamiko Group. Ages of sedimentary rocks were determined by radiolarians, and granite age by K-Ar radiometric dating of biotite and whole rock.

Reported Minerals

Mineral Assemblages

  • Quartz - Feldspar - Muscovite - Adularia - Brookite - Anatase - Rutile
  • Quartz - Feldspar - Montmorillonite

Details of the mine

Silica stone was mined.

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