Iron(III) Oxide, also known as Ferric Oxide, is one of sixteen iron oxides, which are composed of iron combined with oxygen. The mineral form is Hematite, which composes most of the natural iron in nature.
The molecular structure of iron(III) oxide is Fe2O3, which is two iron atoms combined with three oxygen atoms. It is most often seen as rust, although this is more properly called hydrated iron(III) oxide, as the oxygen combines in the form of water. It is a simple chemical compound, which either connects with other iron oxides to form a mineral structure, or remains disconnected, as in rust. Generally, iron(III) oxide does not form a complex molecular shape unless it combines with itself or another chemical compound.