Iron(II,III) oxide is a chemical compound. It can be used as an iron ore (source of a material) called magnetite.. It is black and brittle. It can oxidize to red iron(III) oxide after some time. It is attracted to magnets. It is a compound that contains iron in two different oxidation states; some of the iron atoms are in a +2 oxidation state and some are in a +3 oxidation state.