Mangano-cummingtonite
Ashio village, Nikko city, Tochigi pref., Japan
Field of view: 5mm. Prismatic mangano-cummingtonite. The white prisms exhibiting perfect cleavage are mangano-cummingtonite or Mn-bearing tremolite. The black part at the lower left is manganese dioxide formed by weathering.
Recovered from a chert-hosted bedded manganese deposit subjected to Albite-Epidote-hornfels contact metamorphism. Formed in the early Paleocene (64 Ma).
Manganocummingtonite from this location was described in 1961 as manganese amphibole.
Other localities
- Taguchi Mine (Bedded Mn, AM facies)
- Gozaisho Mine (Bedded Mn, EA facies)
- Kyurazawa Mine (Mn skarn, Prismatic)
- Oashi Mine (Mn skarn, Fibrous)