Any of various compounds of oxygen and iron, including FeO, Fe2O3, and Fe4O5; often formed in the presence of water; as much as fifty times the volume of pureiron; used as a pigment, with various hues depending on the chemical composition, ranging fromyellowto orange, red, and dark brown. Also known as rust. See also Indian red, iron stain, rust jacking. (Bucher, 1996)
