Iron occurs mainly as oxide ores, though it is also found in smaller quantities as its sulfide and carbonate. These other ores are usually first roasted to convert them into the oxide. On a world scale the most important ore is haematite (Fe2O3), but in New Zealand the starting materials are magnetite (Fe3O4) and titanomagnetite (Fe2TiO4). The oxides are reduced with carbon from coal, through t...