Hematite, an iron ore, is one of the more common minerals. The color of most red and brown rock and sand, such as sandstone, is caused by small amounts of Hematite (think of iron oxidizing into rust). It is also one of the primary inclusions for numerous red-tinted/colored minerals. In crystallized form its colors are steel or silver gray to black, and in earthy and massive form it is red to brown. Its luster is metallic to earthy. The following are three popular and collectable varieties:
Specularite is a micaceous or flaky stone that is a sparkling silver gray.
Hematite Rose is a circular arrangement of bladed crystals giving the appearance of rose petals.
Kidney Ore is the massive botryoidal form, giving the appearance of lumpy kidney-like masses.
The crystal system for Hematite is Hexagonal. Its crystal forms are quite varied, including tabular, micaceous or platy, dendritic and in rosettes, massive, botryoidal, oolitic (aggregate composed of very small spheroids), stalactitic, radiating and pseudomorphs after other minerals.
Hematite has numerous locations, the most notable being Brazil, England, Italy, Morocco, Switzerland and the USA (Arizona, Michigan).