Iron oxide is a chemical compound formed of iron and oxygen. Altogether there are about 16 types of iron oxide and oxyhydroxide. This oxide plays a significant role in many natural biological and geological processes and is widely used by humans as iron ore, pigment, catalyst in thermite. Iron oxide with molar mass 231 533 g / mol And the appearance of this combination is black powder. The general formula for this compound is Fe3O4. Two other compounds, one FeO 2, are a rare compound and the other is a trivalent iron oxide with the formula (Fe2O3) in chemistry called hematite, and is found in ancient Persian texts called Shaden.