Rust is a general term for a series of
iron oxides, usually red oxides, formed by the reaction of
iron and
oxygen in the presence of water or air moisture. Several forms of rust are distinguishable visually and by
spectroscopy, and form under different circumstances.
[1] Rust consists of hydrated
iron(III) oxides Fe2O3·nH2O and
iron(III) oxide-hydroxide (FeO(OH), Fe(OH)3). Rusting is the common term for
corrosion of iron and its alloys, such as
steel. Other metals undergo equivalent corrosion, but the resulting oxides are not commonly called rust. Given sufficient time, oxygen, and water, any iron mass eventually converts entirely to rust and disintegrates.