A silvery malleable and ductile metallic transition element; a.n. 26; r.a.m. 55.847; r.d. 7.87; m.p. 1535°C; b.p. 2750°C. The main sources are the ores haematite (Fe₂O₃), magnetite (Fe₃O₄), limonite (FeO(OH)_nH₂O), ilmenite (FeTiO₃), siderite (FeCO₃), and pyrite (FeS₂). The metal is smelted in a blast furnace to give impure pig iron, which is further processed to give cast iron, wrought iron, and various types of steel. The pure element has three crystal forms: alpha-iron, stable below 906°C with a body-centred-cubic structure; gamma-iron, stable between 906°C and 1403°C with a nonmagnetic face-centred-cubic structure; and delta-iron, which is the body-centred-cubic form above 1403°C. Alpha-iron is ferromagnetic up to its Curie point (768°C). The element has nine isotopes (mass numbers 52–60), and is the fourth most abundant in the earth’s crust. It is required as a trace element (see essential element) by living organisms. Iron is quite reactive, being oxidized by moist air, displacing hydrogen from dilute acids, and combining with nonmetallic elements. It forms ionic salts and numerous complexes with the metal in the +2 or +3 oxidation states. Iron(VI) also exists in the ferrate ion FeO₄²⁻, and the element also forms complexes in which its oxidation number is zero (e.g. Fe(CO)₅).

https://www.webelements.com/iron/ Information from the WebElements site