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Kiyokawa Mine

Nippara, Okutama city, Nishi-tama county, Tokyo, Japan


High-T zeolite facies bedded manganese deposit

Chert-hosted bedded manganese deposit in a chert block of the Early Jurassic (180 Ma) Ohirayama unit, a member of the Southern Chichibu accretionary complex. The Ohirayama unit has been subjected to weak Prehnite-Pumpellyite to Zeolite facies metamorphism as a low grade part of the Sambagawa metamorphic belt in the Late Cretaceous (100 Ma). The age of chert is Permian Guadalupian (270 Ma) to Early Jurassic (200 Ma). Ages of sedimentary rocks were determined by radiolarians, and metamorphic age by K-Ar or Ar-Ar radiometric dating of muscovite.

Reported Minerals

Mineral Assemblages

  • Hausmannite - Jacobsite - Pyrochroite - Manganosite - Rhodochrosite
  • Hausmannite - Wiserite
  • Rhodonite - Rhodochrosite - Quartz


  • 1964: Started to mine.
  • 1979: The mine was closed.
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