A mineral form of iron(III) oxide, Fe2O3. It is the most important ore of iron and usually occurs in two main forms: as a massive red kidney-shaped ore (kidney ore) and as grey to black metallic crystals known as specular iron ore. Haematite is the major red colouring agent in rocks; the largest deposits are of sedimentary origin. In industry haematite is also used as a polishing agent (jeweller’s rouge) and in paints.