Iron oxide

Iron oxides are compounds of iron and oxygen, including iron(II) oxide, iron(III) oxide, and mixed-valence magnetite. Their structures and properties vary with iron’s oxidation state and the arrangement of atoms.

Iron(II) oxide: A black iron oxide with the formula FeO, containing iron in the +2 oxidation state. It is the simplest common iron oxide by oxidation state, though its composition is often nonstoichiometric.
Iron corrosion: The electrochemical deterioration of iron through reactions with its environment. Corrosion commonly converts metallic iron into hydrated iron oxides and oxyhydroxides.
Iron ore: A naturally occurring material from which metallic iron can be extracted economically. Hematite and magnetite are the principal iron oxide ores used in ironmaking.
Hematite: A reddish to black mineral consisting mainly of α-Fe₂O₃. It is a stable iron(III) oxide and a major source of iron ore.
Rust: A flaky mixture of hydrated iron oxides and iron oxyhydroxides formed by iron corrosion. It is the familiar environmental product of iron oxidation, not a single pure compound.
Iron(III) oxide: An iron oxide with the formula Fe₂O₃, in which iron is in the +3 oxidation state. Its polymorphs include hematite, a widespread mineral and the main ore of iron.
Oxidation-reduction reaction: A chemical reaction involving electron transfer and changes in oxidation state. Iron oxidation and oxygen reduction drive the formation of many iron oxides.
Blast furnace: A tall industrial furnace that reduces iron ore with carbon monoxide to produce molten iron. Iron oxides are reduced there on a large scale to supply iron and steel production.
Maghemite: A magnetic, vacancy-rich iron(III) oxide with a structure related to magnetite. It commonly forms when magnetite oxidizes while retaining a similar crystal framework.
Great Oxidation Event: A major rise in atmospheric oxygen on Earth roughly 2.4 billion years ago. Oxygenation enabled extensive oxidation and deposition of iron minerals in ancient oceans.

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