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CategoryOxide mineral
(repeating unit)
Strunz classification4.BB.10
Crystal systemTetragonal
Crystal classDitetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)
Space groupI41/amd
Unit cella = 5.76 Å
c = 9.46 Å; Z = 4
Formula mass228.81 g/mol
ColorBrownish black, grayish.
Crystal habitMassive - granular - common texture observed in granite and other igneous rock. pseudo octahedral - crystals show an octahedral outline.
TwinningRepeated twins on {112}
Cleavage[001] Perfect
FractureUneven - flat surfaces (not cleavage) fractured in an uneven pattern.
Mohs scale hardness5.5
StreakDark reddish brown
DiaphaneityOpaque, transparent on thin edges
Specific gravity4.7 - 4.84, average = 4.76
Optical propertiesUniaxial (-)
Refractive indexnε = 2.15, nω = 2.46
Birefringenceδ = 0.31
Other characteristicsAnisotropism: Distinct, bireflectance: weak; O = light gray; E = dark gray.

Hausmannite is a complex oxide of manganese containing both di- and tri-valent manganese. The formula can be represented as Mn2+Mn3+2O4. It belongs to the spinel group and forms tetragonal crystals. Hausmannite is a brown to black metallic mineral with Mohs hardness of 5.5 and a specific gravity of 4.8.

The type locality is Oehrenstock (Öhrenstock), Ilmenau, Thuringian Forest, Thuringia, Germany, where it was first described in 1813.[2] Locations include Batesville, Arkansas, US; Ilfeld, Germany; Langban, Sweden; and the Ural Mountains, Russia.[1] High quality samples have been found in South Africa and Namibia where it is associated with other manganese oxides, pyrolusite and psilomelane and the iron-manganese mineral bixbyite. Wilhelm Haidinger (1827) named it in honour of Johann Friedrich Ludwig Hausmann (1782–1859), Professor of Mineralogy, University of Göttingen, Germany.[2]

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