The basic constituent of the ferromagnetic spinels or ferrites. FeO, Fe₂O₃, and Fe₃O₄have melting points ranging from that of FeO at 1,420 degrees C to that of Fe₂O₃at 1,565 degrees C. Used extensively for producing colors in glasses, glazes, and enamels. Iron and iron oxides produce brown or reddish colors in ceramic mixtures if they are fired in an oxidizing atmosphere, and greenish or bluish colors if fired in a reducing atmosphere. Iron oxides are fluxing and coloring materials. Larger particles produce brown or black spots, which, particularly in whiteware, are undesirable. Much care is taken to remove iron and iron oxides from the raw materials and from the bodies used for whiteware manufacture.