| Noun | 1. | 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 manganese tetroxide - an oxide of manganese found naturally as hausmannite |