Mount Obira
Moroyama city, Iruma county, Saitama pref., Japan
Occurrence
Oxidation zone of Pumpellyite-Aclinolite facies bedded manganese deposit
Chert-hosted bedded manganese deposit in a chert block of Kashiwagi Unit, a member of Northern Chichibu Belt. Probably it beongs to Tate Subunit of Kashiwagi Unit.
Outcrop of bedded chert of Kashiwagi Unit around the adit. The bedding planes of bedded chert are clear, and its surface turns black by manganese dioxide. There is no clear record on this mine but it is said that this deposit was mined approximately 100 years ago and closed because of high Fe content.
Reported Minerals
- Mn dioxide
- Caryopilite
- Greenalite
- Rhodochrosite
Mineral Assemblages
- Caryopilite - Greenalite - Rhodochrosite
History
- late 19 century to early 20 century: Mined.
Localities
- Nakano-Tsuchiyama Mine (Gossan zone)
- Kitamukai-Jizo (Gossan zone)
- Mount Obira (Gossan zone)
Related Occurrences
- Bedded Mn (Diagenesis)
- Bedded Mn (Low-T zeolite facies)
- Bedded Mn (High-T zeolite facies)
- Bedded Mn (Prehnite-Pumpellyite facies)
- Bedded Mn (Pumpellyite-Actinolite facies)
- Bedded Mn (Greenschist facies)
- Bedded Mn (Epidote-Amphibolite facies)
- Bedded Mn (Amphibolite facies)