Iron Oxides And Oxide-Hydroxides Are Widespread In Nature, Play An Important Role In Many Geological And Biological Processes, And Are Widely Utilized By Humans, E.G., As Iron Ores, Pigments, Catalysts, In Thermite ( See The Diagram) , Haemoglobin. Common Rust Is A Form Of Iron( Iii) Oxide. Iron Oxides Are Widely Used As Inexpensive, Durable Pigments In Paints, Coatings And Colored Concretes. Colors Commonly Available Are In The " Earthy " End Of The Yellow/ Orange/ Red/ Brown/ Black Range.