The principal iron minerals are hematite (Fe2O3), magnetite (Fe3O4), limonite (Fe2O3.H2O) and siderite (FeCO3). The most common natural iron compounds are pyrite (FeS2) and ilmenite (FeO.TiO2) but are not suitable for the element extraction.

The major deposits of iron are in the USA, France, Germany, Great Britain, Austria, Sweden and Russia. Other important producers are Brazil, Chile, Cuba, Venezuela and Canada. This element occurs in almost all the rocks (though in small amounts) and in living animals and plants. It is also easy to find in natural water springs.