Hematite (or haematite)Hematite is the most important ore mineral of iron. It is an oxide mineral and is found in a variety of colours, with red, orange and brown occurring when the iron in hematite begins to rust. There are also several forms of hematite, some of which are: kidney ore, a massive, botryoidal (lumpy) or reniform (kidney shaped) form; specularite, a micaceous (flaky) form; oolitic, a sedimentary form composed of small rounded grains; red ochre, a red earthy form. Because of its red colour when powdered, hematite lends itself well to use as a pigment, and it was used by ancient cultures as a colouring for red and brown paint.
Large ore bodies of hematite are usually of sedimentary origin, and it is widely distributed in sedimentary rocks as a cement. High grade ore bodies can be found in metamorphic rocks as a result of contact metasomatism. Hematite is also as an accessory mineral in igneous rocks. The red colouring of soils all over the planet is due to hematite.
Chemical composition - Fe