Iron ore deposits are located in sedimentary rocks. They are formed from chemical reactions that combined iron and oxygen in marine and fresh waters. Hematite (Fe2O3) and magnetite (Fe3O4) are the two important minerals in iron oxides deposits. Iron ore are formed through chemical reactions that utilize iron and oxygen, where the gas combine with iron in dissolved form to produce Hematite and Magnetite which are deposited in the sea floor as banded iron formations. During a volcanic eruption more iron ore deposits are located near its foot
Working slowly over many years, groundwater travels along small cracks. The water dissolves and carries away the solid rock. This gradually enlarges the cracks.
