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Mount Futago

Ogano city, Chichibu county, Saitama pref., Japan



Calcite deposit in recrystallized limestone block of Futagoyama Limestone, one of a memeber of Sumaizuku Unit of Northern Chichibu Belt, Jurassic accretoinary complex.

Mount Futago

Old mine produced transparent calcite crystals for optical materials. The walls at the both sides are composed of crystalline limestone of Futagoyama Limestone. The size of calcite crystals is up to a few cm. The distribution of the recrystallized calcite is restricted, and fresh fossils are in other parts of this limestone block.

Reported Minerals

Mineral Assemblages

  • Limestone(Host) - Calcite


  • 1910's: Toyama pharmacy at Asakusa-Kaminarion, Tokyo, mined calcite for medical use.
  • Tokijiro Mizuno made the first Japanese nicol prism using calcite specimens supplied by Toyama pharmacy.
  • After mined by a few people, the mine was closed.


  • Mount Futago (Limestone, Recrystalized)
  • Koma (Calcareous sandstone, Veins)

Related Occurrences

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