Black Iron Oxide
n FeO·Fe2O3 or Fe3O4. Pigment Black 11 (77499). Two black oxides of iron are used, namely, the natural mineral, magnetite, and the artificially produced oxide. Both types are magnetic. Neither possesses outstanding opacity. Magnetite consists of about 95% Fe3O4. Artificial back oxide consists of a mixture of ferric oxide (Fe2O3) and ferrous oxide (FeO). (Kirk-Othmer encyclopedia of chemical technology: pigments-powders (1996). Wiley, New York).