Iron oxides are chemical compounds composed of iron and oxygen. There are sixteen known iron oxides and oxyhydroxides.
Iron oxides and oxyhydroxides are widespread in nature and play an important role in many geological and biological processes.
They are used as iron ores, cosmetic pigments, tattoo inks, catalysts, and in thermite, and occur in hemoglobin. Iron oxides are inexpensive and durable pigments in paints, coatings and colored concretes.