Manganese

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Manganese Mn is an element that occurs rarely in the native state.

Specific gravity: 7.01 calculated
Hardness: 6½
Streak: Dark grey
Colour: Steel-grey
Melting point: 1250^oC
Environments

Placer deposits

Manganese has not been approved as a mineral species by the IMA.
It tarnishes on exposure to air and, when heated, oxidises to hausmannite (ChC).
The most stable oxidation state is Mn²⁺, which is a pale pink color in aqueous solutions. Also important is Mn⁴⁺, brown/black, which is found in ramsdellite, and Mn⁷⁺ found in the purple permanganate anion (Mn⁷⁺O₄)^1–. The Mn⁶⁺ oxidation state is green (ChC).
The abundance in the Earth's crust is 0.1% by weight, 360 parts per million by moles (ChC).

Localities

The first recorded locality was in unnamed placers, at Aldan, Sakha Republic, Russia. Manganese occurred as angular grains up to 0.8mm, in platinum group mineral-gold placers derived from serpentinised ultramafic rocks (olivine - orthoclase picrite) in a matrix of tephroite, spessartine, chromium-rich hausmannite and an unnamed manganese carbide, and associated with tephroite, spessartine, orthoclase, olivine and gold (AM88.933, Mindat).

Manganese-bearing minerals include:

Sulphides