Manganese

manganese

hausmannite

ramsdellite

tephroite

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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 - the sulphide anion is S^2-
Sulphosalts - sulphide minerals with the general formula AmBnXp, where A represents a metal , B usually represents semi-metal and X is sulphur or rarely selenium and/or tellurium
Oxides - the oxide anion is O^2-
Hydroxides - the hydroxide anion is (OH)^-
Chlorides - the chloride anion is Cl^-
Carbonates - the carbonate anion is (CO₃)^2-
Monoborates - with a single boron anion (BO₃)^3- or B(O,OH)₄
Diborates - with double boron triangles and/or tetrahedra
Megaborates
Sulphates - the sulphate anion is (SO₄)^2-
Tellurates - salts of telluric acid H₆Te⁶⁺O₆
Tellurites - the tellurite anion is (Te⁴⁺O₃)^2-
Sulphites - the sulphite anion is (SO₃)^2-
Phosphates - the phosphate anion is (P⁵⁺O₄)^3-
Arsenates - the arsenate anion is (As⁵⁺O₄)^3-
Hydrogen Arsenates - the hydrogen arsenate anion is (As⁵⁺O₃OH)^2-
Vanadates - the vanadate anion is (V⁵⁺O₄)^3-
Antimonates - the antimonate anion is (Sb⁵⁺O₃)^-
Arsenites - the arsenite anion is (As³⁺O₃)^3-
Nesosilicates - insular (Si⁴⁺O₄)^4- groups
Sorosilicates - (Si⁴⁺₂O₇)^6- groups
Cyclosilicates - (Si⁴⁺_nO_3n)^2n-
Inosilicates - Single Chain - (Si⁴⁺_nO_3n)^2n-
Inosilicates - Double Chain - (Si⁴⁺_4nO_11n)^6n-
Inosilicates - Multiple Chains
Phyllosilicates - (Si⁴⁺₂O₅)^2- groups
Tectosilicate - [Al³⁺_xSi⁴⁺O_yO_(2x+2y)]^x−
Unclassified silicates

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