Hematite is the main ore of iron and commonly has the formula Fe₂O₃.
Hematite is an iron oxide mineral containing iron in the +3 oxidation state. It can occur as metallic-gray crystals, earthy red masses, or thin red coatings. The name comes from the Greek word haima, meaning blood, referring to the red streak or powder produced by many specimens.
Hematite has been mined for thousands of years as a pigment and has become one of the most important industrial iron ores. It occurs in sedimentary iron formations, hydrothermal deposits, igneous rocks, and soils. Its red color also gives Mars much of its characteristic surface appearance.
Magnetite is another major iron ore and is strongly magnetic, whereas hematite is usually weakly magnetic or nonmagnetic. Limonite is a mixture of hydrated iron oxides rather than a single fixed mineral species.