Iron(III) oxide

Iron(III) oxide," also known as **ferric oxide** or **Fe₂O₃**, is a common, naturally occurring iron compound found as the mineral hematite[3][9]. It consists of iron in the +3 oxidation state (Fe³⁺) bound to oxygen, forming a reddish-brown solid that is insoluble in water and has the formula Fe₂O₃[3][7][9]. Ferric iron (Fe³⁺) is a chemical state of elemental iron, not a receptor, enzyme, transporter, or specific biological macromolecule. Instead, ferric iron serves as an ionic form of iron present in biological systems—transported in blood mainly by binding to the protein transferrin and stored in ferritin for future physiological use[4][2]. In medicine and physiology, the relevant "targets" for ferric iron are the proteins that bind, transport, or reduce Fe³⁺, such as **transferrin receptors** (e.g., TFR1), **ferritin**, **ferroportin**, and enzymes in iron homeostasis, but "ferric iron" itself is not a molecular therapeutic target[4][2][10]. The entry appears to be a confusion between the iron ion and the relevant protein targets or transporters associated with iron metabolism.

Other names

ferric oxidered iron oxideiron trioxideoxo(oxoferriooxy) ironFe₂O₃