Hausmannite
| Hausmannite | |
|---|---|
Hausmannite sample from the collection of the National Museum, Prague, Czech Republic
|
|
| General | |
| Category | Oxide mineral |
|
Formula (repeating unit) |
Mn2+Mn3+2O4 |
| Strunz classification | 4.BB.10 |
| Crystal system | Tetragonal |
| Crystal class | Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) |
| Space group | I41/amd |
| Unit cell | a = 5.76 Å c = 9.46 Å; Z = 4 |
| Identification | |
| Formula mass | 228.81 g/mol |
| Color | Brownish black, grayish. |
| Crystal habit | Massive - granular - common texture observed in granite and other igneous rock. pseudo octahedral - crystals show an octahedral outline. |
| 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 | |
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. Locations include Batesville, Arkansas, US; Ilfeld, Germany; Langban, Sweden; and the Ural Mountains, Russia. 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.
...
Wikipedia