Haematite

Haematite, mineral and the most abundant ore of iron, composed of ferric oxide, Fe₂O₃. It is widely distributed over the world, occurring in rocks of all ages. Among the most important haematite regions in the world are those located along the shores of Lake Superior in Michigan and extensive deposits in Brazil.

Haematite occurs in rhombohedral crystals. In massive formations it is called specular iron and in earthy forms, red ochre. The crystals are translucent, ranging in colour from dark grey to black, with a brilliant metallic lustre; the earthy varieties are lustreless and red. The hardness ranges from 5.5 to 6.5 and the relative density from 4.2 to 5.25.

In addition to being the principal ore of iron, haematite is a constituent of a number of abrasives and pigments.