Magnolia

Hausmannite is a complex oxide, or a mixed oxide, of manganese containing both di- and tri-valent manganese. Its chemical formula can be represented as Mn^IIMn^III₂O₄, or more simply noted as MnO·Mn₂O₃, or Mn₃O₄, as commonly done for magnetite (Fe₃O₄), the corresponding iron oxide. 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.^[3] Locations include Batesville, Arkansas, US; Ilfeld, Germany; Langban, Sweden; and the Ural Mountains, Russia.^[2] 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.^[3]

Image gallery

• 
  Hausmannite from Wessels mine, Kalahari manganese fields, Northern Cape Province, South Africa
• 
  Crystal structure of hausmannite
• 
  Cluster from Wessels mine, Hotazel, Kalahari manganese fields, Northern Cape Province, South Africa
• 
  Ettringite crystal on a matrix of hausmannite and hematite, coated by oyelite

References