limonite an ore of iron is brought into
Iron ore Sulfur can be removed from ores by roasting and washing. Roasting oxidizes sulfur to form sulfur dioxide which either escapes into the atmosphere or can be washed out. In warm climates it is possible to leave pyritic ore out in the rain. The combined action of rain, bacteria, and heat oxidize the sulfides to sulfuric acid and sulfates, which are water-soluble and leached out (Turner 1900, pp.Â 77). However, historically (at least), iron sulfide (iron pyrite FeS 2), though a common iron mineral, has not been used as an ore for the production of iron metal. Natural weathering was also used in Sweden. The same process, at geological speed, results in the gossan limonite ores.