Iron(III) oxide

Iron(III) oxide (Fe₂O₃) is a dark red to reddish-brown solid composed of iron and oxygen. It occurs naturally as hematite and serves as an iron ore and pigment.

Iron: Iron is a chemical element with atomic number 26 and a metal central to steelmaking and biology. Iron atoms occupy the cation sites in Fe₂O₃ and supply its characteristic oxidation state.
Iron ore: Iron ore is rock or mineral material mined for economically recoverable iron. Hematite is one of the principal ores from which iron is extracted.
Iron(II) oxide: Iron(II) oxide (FeO) is a black iron oxide in which iron has the formal oxidation state +2. Its lower iron oxidation state contrasts with the +3 state in Fe₂O₃.
Redox reaction: A redox reaction transfers electrons as oxidation and reduction occur together. Iron extraction and thermite both transform Fe₂O₃ through coupled oxidation and reduction.
Banded iron formation: A banded iron formation is an ancient sedimentary rock made of alternating iron-rich and silica-rich layers. Many large hematite deposits formed through geological alteration of these iron-rich rocks.
Oxygen: Oxygen is a chemical element with atomic number 8 that readily forms compounds with metals. Oxygen atoms combine with iron in the 3:2 ratio that defines Fe₂O₃.
Blast furnace: A blast furnace is a shaft furnace that reduces iron oxides with carbon monoxide to produce molten iron. Its carbon monoxide removes oxygen from hematite during ironmaking.
Iron(II,III) oxide: Iron(II,III) oxide (Fe₃O₄), also called magnetite, contains both Fe²⁺ and Fe³⁺ ions. Magnetite combines two iron oxidation states and is strongly magnetic, unlike hematite.
Aluminothermic reaction: An aluminothermic reaction uses aluminum to reduce a metal oxide, releasing substantial heat. Aluminum transfers oxygen from Fe₂O₃ to form alumina and metallic iron.
Oxygenation of Earth's atmosphere: The oxygenation of Earth's atmosphere was the rise of atmospheric oxygen driven largely by photosynthetic microorganisms. Early oxygen reacted with dissolved iron, helping precipitate iron oxides in ancient oceans.

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