Janggunite: Properties and Occurrences

Janggunite is a rare manganese oxide mineral with formula Mn5-x(Mn, Fe)1+xO8(OH)6. It is an orthorhombic black mineral containing hydrogen, iron, manganese, and oxygen. It was first described in 1975 for an occurrence in the Janggun mine, Bonghwa-gun, Gyeongsangbuk-do, South Korea and named for the locality.

General Information

  • Category: Oxide mineral
  • Formula: Mn5-x(Mn, Fe)1+xO8(OH)6
  • Crystal system: Orthorhombic
  • Space group: Pman

Properties

Janggunite mineral belongs to Oxide minerals. It has Mohs Hardness between 2-3.

  • Color: Black
  • Cleavage: Perfect, one direction
  • Tenacity: Fragile
  • Mohs scale hardness: 2 – 3
  • Luster: Dull
  • Streak: Brownish black to dark brown
  • Specific gravity: 3.59
  • Optical properties: Biaxial

Occurrence: Formed at a late stage of oxidation in a cementation zone of a manganese deposit.

Association: Nsutite, todorokite, calcite, rhodochrosite

 

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