Iron(III) oxide

Chemical Properties

Treatment of iron(III) solutions with alkali leads to precipitation of the red-brown hydrated iron(III) oxide which when ignited above 200° leaves the red-brown oxide a-Fe2O3. This oxide occurs naturally as haematite ; it finds uses in red pigments (ochre, Venetian red) and as a polishing agent in rouge. It has a melting point of 1565°, density of 5.24 and heat of formation of - 196.5 kcal mole-1.