Mangano-cummingtonite
Kusagyu, Kanuma city, Tochigi pref., Japan
Field of view: 5mm. Mangano-cummingtonite associated with rhodonite. The white acicular crystals with perfect cleavage are mangano-cummingtonite or Mn-bearing tremolite. The surrounding massive pink host is aggregate of rhodonite and quartz. The black parts are dirt of manganese dioxide by weathering.
Recovered from a chert-hosted bedded manganese deposit subjected to Hornblende-hornfels facies contact metamorphism. Formed in the Late Cretaceous (83 Ma).
Manganocummingtonite from this location was described in 2008 as Mn-bearing tremolite.
Other localities
- Taguchi Mine (Bedded Mn, AM facies)
- Gozaisho Mine (Bedded Mn, EA facies)
- Kyurazawa Mine (Mn skarn, Prismatic)
- Oashi Mine (Mn skarn, Fibrous)