Iron oxide is a compound formed when iron reacts with oxygen. There are several different forms of iron oxide, including:

* Hematite (Fe₂O₃): The most common form of iron oxide, also known as rust.

* Magnetite (Fe₃O₄): A magnetic form of iron oxide.

* Goethite (FeO(OH)): A hydrated form of iron oxide.

While these compounds contain oxygen as well, the metal component is always iron.