Hagidaira Mine

Occurrence

Hornblende-hornfels facies bedded manganese deposit

Chert-hosted bedded manganese deposit in the Late Triassic (220 Ma) to Early Jurassic (175 Ma) chert block of the Late Jurassic (145 Ma) Kurohone-Kiryu Unit. The deposit has been subjected to Hornblende-hornfels facies contact metamorphism by the Sori granodiorite in the Late Cretaceous (90 Ma), and W, Te, Bi were supplied. Slate near this deposit was metamorphosed to Cordierite-bearing hornfels. The Kurohone-Kiryu Unit corresponds to the Kanayama Unit of the Tamba-Mino-Ashio accretionary complex. The Sori granodiorite is S-type (Ilmenite-series). Approximately 3 km apart from the Sori granodiorite, the heat source. Ages of sedimentary rocks were determined by radiolarians, and granodiorite by K-Ar or Ar-Ar radiometric dating of biotite.

Reported Minerals

• Tephroite
• Alleghanyite
• Rhodochrosite
• Manganosite
• Alabandite
• Rhodonite
• Pyroxmangite
• Spessartine
• Pyrophanite
• Hübnerite
• Pyrite
• Pyrrhotite
• Chalcopyrite
• Galena
• Sphalerite
• Gersdorffite
• Cosalite
• Joséite(Joseite)
• Nickeline
• Bustamite
• Vivianite
• Opal

Mineral Assemblages

• Tephroite - Alleghanyite - Rhodochrosite - Manganosite - Alabandite
• Rhodonite - Pyroxmangite - Spessartine - Quartz
• Rhodonite - Spessartine - Pyrophanite - Hübnerite - Sphalerite

History

• 1895: Mr. Sakamoto, a village person, discovered the deposit and mined manganese oxide ore.
• 1951: Started to mine maganese ore.