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Hausmannit 1.jpg
Hausmannite sample from the collection of the National Museum, Prague, Czech Republic
Category Oxide mineral
(repeating unit)
Strunz classification 04.BB.10
Crystal symmetry Tetragonal - ditetragonal dipyramidal
H-M symbol: (4/m 2/m 2/m)
Space group: I 41/amd
Unit cell a = 5.76 Å, c = 9.46 Å; Z=4
Formula mass 228.81
Color Brownish black, grayish.
Crystal habit Massive - granular - common texture observed in granite and other igneous rock. pseudo octahedral - crystals show an octahedral outline.
Crystal system Tetragonal
Twinning Repeated twins on {112}
Cleavage [001] Perfect
Fracture Uneven - flat surfaces (not cleavage) fractured in an uneven pattern.
Tenacity Brittle
Mohs scale hardness 5.5
Luster Submetallic
Streak Dark reddish brown
Diaphaneity Opaque, transparent on thin edges
Specific gravity 4.7 - 4.84, average = 4.76
Optical properties Uniaxial (-)
Refractive index nε = 2.15, nω = 2.46
Birefringence δ = 0.31
Other characteristics Anisotropism: Distinct, bireflectance: weak; O = light gray; E = dark gray.
References [1][2][3]

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, USA; 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]


Crystal structure of hausmannite
Hausmannite from Wessels Mine, Kalahari manganese fields, Northern Cape Province, South Africa (size: 5.8 x 4.3 x 3.5 cm)