Manganosite Locality: Långban , Filipstad , Värmland , Sweden ( Locality at mindat.org ) Size: 5.8 x 3.7 x 3.5 cm. Manganosite is a rare manganese oxide and usually is found as irregular grains or masses. This very rich, old-time specimen from Langban, Sweden features rare octahedrons, subhedral crystals and massive manganosite. The fresh, broken emerald-green crystals darken to brown or black upon exposure. This is a very rich, very uncommon example of the rare species and world-famous locale. Ex. Dennis Mullane Collection and accompanied by an older, faded Burminco label from the 1950s or 1960s. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Manganosite
Manganese(II) oxide — a rare green mineral described in 1817 from the Harz Mountains.
Intro adapted from Wikipedia (CC BY-SA).
Manganosite is an IMA-recognized mineral species in the oxides & hydroxide class, with the chemical formula MnO.
It crystallizes in the cubic crystal system (space group Fm3m). It is a member of the Rocksalt structural group.
Key properties: Mohs hardness 5.5; specific gravity 5.364; Brown streak; Vitreous to adamantine, dull on exposure luster; refractive index 2.165; optically isotropic.
IMA symbol Mng, grandfathered status — known before the IMA’s founding, named in 1874.
An alteration product of rhodochrosite or other manganese minerals, developed during oxygen-deficient metamorphism of manganese-bearing deposits; in marine manganese nodules.
It is found associated with Pyrochroite, manganite, dolomite (Långban, Sweden); pyrochroite, hausmannite, garnet, dolomite (Nordmark, Sweden); franklinite, willemite, zincite (Franklin.
As an oxide of manganese.