Hausmannite

hausmannite

neotocite

spinel

jacobsite

Images

Formula: Mn2+Mn3+2O4
Multiple oxide with a distorted spinel structure, although it is not a member of the spinel group (Mindat). Manganese mineral.
Specific gravity: 4.83 to 4.85
Hardness: 5½
Streak: Dark reddish brown, dark brown
Colour: Brown-black
Solubility: Soluble in hot hydrochloric acid with the evolution of Cl2.
Epitaxy: Hausmannite and jacobsite have been found as oriented intergrowths.
Common impurities: Zn,Fe,Ca,Ba,Mg
Environments:

Metamorphic environments
Hydrothermal environments

Hausmannite is a primary mineral in hydrothermal veins. It may also be produced by metamorphism of manganiferous rocks.

Localities

At the Woods mine, New South Wales, Australia, hausmannite forms by oxidation and loss of SiO2 from neotocite and tephroite. (AJM 15.1&2.15)

At the type locality, Oehrenstock, Langewiesen, Ilmenau, Ilm-Kreis, Thuringia, Germany, hausmannite occurs in a manganese ore deposit.

At Ilfeld, Harztor, Nordhausen, Thuringia, Germany, hausmannite pseudomorphs after manganite have been found with minor baryte (KL p147).

At the Wyndham pit, Bigrigg, Egremont, Copeland, Cumbria, England, UK, hausmannite is associated with hematite (SY p162).

Alteration

braunite to hausmannite, SiO2 and O2
3Mn2+Mn3+6O8(SiO4) ⇌ 7Mn2+Mn3+2O4 +3SiO2 + O2
(AM80.565)

braunite to hausmannite, rhodonite and O2
2Mn2+Mn3+6O8(SiO4) ⇌ 4Mn2+Mn3+2O4 + 2Mn2+SiO3 + O2
A higher temperature favours the forward reaction
(AM80.565).

braunite to tephroite, hausmannite and O2
3Mn2+Mn3+6O8(SiO4) ⇌ 3Mn2+2(SiO4) + 5Mn2+Mn3+2O4 + 2O2
(AM80.571)

hausmannite and O2 to bixbyite
4Mn2+Mn3+2O4 + O2 ⇌ 6Mn2O3
(AM80.560-575)

hausmannite and quartz to rhodonite and O2
2Mn2+Mn3+2O4 + 6SiO2 ⇌ 6Mn2+SiO3 + O2
(AM80.571)

hausmannite and rhodonite to tephroite and O2
2Mn2+Mn3+2O4 + 6Mn2+SiO3 ⇌ 6Mn2+2SiO4 + O2
A higher temperature favours the forward reaction (AM80.565)

manganosite and O2 to hausmannite
6MnO + O2 ⇌ 2Mn2+Mn3+2O4
A higher temperature favours the forward reaction
(AM80.571)

rhodochrosite and O2 to hausmannite and CO2
6MnCO3 + O2 ⇌ 2Mn2+Mn3+2O4 +6CO2
A higher temperature favours the forward reaction (AM80.571)

The diagram below is a Pourbaix diagram for manganese (GSJ). It shows the relationship between akhtenskite MnO2, bixbyite Mn2O3 and hausmannite Mn3O4.

Pourbaix manganese.jpg






















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