Iron oxide black (E 172, synonymous CI Pigment Black 11, triiron-tetraoxide, black iron oxide, ferrous ferric oxide, magnetite, Colour Index 77499) is identical to the active substance iron(II,III) oxide (International Union of Pure and Applied Chemistry (IUPAC) name, Chemical Abstracts Service (CAS) number 1317-61-9, molecular formula FeO·Fe2O3, molecular weight 231.55).
Iron oxide black is produced via chemical synthesis using iron oxide yellow (FeO(OH)) or iron oxide red (Fe2O3) and/or iron(II) sulfate as starting chemicals which are converted/reacted in the presence of pure oxygen and caustic soda (precipitation process).
