Hematite

Hematite (AE) or hematite (BE) is the form mineral of Iron (III) oxide, (Fe2O3), one of several iron oxides. The ore sometimes contains slight amounts of titanium also. When shaped into ornaments, it is often known as black diamond.

Hematite (kidney ore) from Michigan Hematite is a very common mineral, colored black to steel and silver-gray, brown to reddish brown, and even red. It is mined as the main ore of iron. Varieties include Bloodstone, Iron Rose, Kidney Ore, Martine, Paint Ore, Specula rite (Secular Hematite), Rainbow Hematite and also Titano-hematite. While the forms of hematite vary, they all have a very rust-red streak. Hematite is harder than pure iron, but much more brittle.

Deposits of grey hematite are usually found in places where there has been standing water and mineral hot springs, such as those in Yellowstone. The mineral can precipitate out of water and then collect in layers at the bottom of the lake, spring, or other standing water. But hematite could also occur without water, as the result of volcanic activity.

History

The name hematite is derived from the Greek word for blood, since sometimes hematite can be red, as in Rouge, a powder zed form of hematite. It shares this root with the word hemoglobin. Hemoglobin is the oxygen-transporting molecule in red blood cells, the iron of which causes blood to be red. The color of hematite lends it well in use as a pigment.

Rainbow Hematite from Brazil Especially nice specimens of hematite come from England, Mexico, Brazil, Australia and then from Lake Superior region of the United States and Canada.

Hematite is an ant ferromagnetic material below the Morin transition at 250K, and a canted antiferromagnet and weakly ferromagnetic above the Morin transition

Clay-sized hematite crystals could also occur as a secondary mineral formed by weathering processes in the soil, and also along with other iron oxides or ox hydroxides such as goethite, is responsible for the red color of many tropical, ancient, and otherwise highly weathered soils.