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Hausmannite
Chemical Formula	Mn2+Mn3+2O4
Species	Oxides & Hydroxides
Crystal System	Tetragonal
Mohs Scale	5
Specific Gravity	4.7-4.84
Color	Brownish black, Grayish.
Streak	dark reddish brown
Luster	Sub-Metallic
Cleavage	Very Good nearly perfect; and indistinct.
Fracture	Irregular/Uneven
Crystal Habit：Massive - Granular - Common texture observed in granite and other igneous rock. Pseudo Octahedral - Crystals show an octahedral outline.

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 (?hrenstock), Ilmenau, Thuringian Forest, Thuringia, Germany. Locations include Batesville, Arkansas, USA; Ilfeld, Germany; Langban, Sweden; and the Ural Mountains, Russia. The best 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.