Manganese(II,III) oxide is the chemical compound with formula Mn3O4. Manganese is present in two oxidation states +2 and +3 and the formula is sometimes written as MnO.Mn2O3. Mn3O4is found in nature as the mineral hausmannite.
Hausmannite - a mineral consisting of manganese tetroxide; a source of manganese atomic number 25, manganese, Mn - a hard brittle grey polyvalent metallic element that resembles iron but is not magnetic; used in making steel; occurs in many minerals
Mineral - solid homogeneous inorganic substances occurring in nature having a definite chemical composition