TrekGEO > Mineral Trail > Koshinetsu region > Nagano pref. > Ryushima Mine

Japanese page

Ryushima Mine

Azumi, Matsumoto city, Nagano pref., Japan


Moderate-T hydrothermal deposit

Mn-dominant moderate temperature hydrothermal deposit formed by Nagawa Granite intruded in Misogawa Complex of Mino Belt. Approximately 2.5 km apart from Nagawa Granite, the heat source.

Ryushima Mine

Outcrop of a kutnahorite vein network in slate of Misogawa Complex. The pale pink network is veins of massive kutnahorite, and euhedral crystals are in open spaces of the vein. Black host is silicified slate. Brownish-black crusts on the outcrop surface at the upper left and the upper right are pyrolusite formed by weathering of kutnahorite.

Reported Minerals

  • Kutnohorite
  • Pyrolusite
  • Pyrite
  • Sphalerite
  • Galena

Mineral Assemblages

  • Kutnohorite - Pyrolusite
  • Kutnohorite - Sphalerite - Galena - Pyrite


  • 1899: Mr. Fukazawa, a local person, found the deposit.
  • 1921: Mr. Amano from Osaka started to mine manganese ore.
  • 1927: Restarted to mine 10-50 t/month ore.
Copyright (c) 2024 NariNari, All Rights Reserved.