Hematite

Hematite

Hematite is a compact form of iron oxide. It varies considerably in compactness and form. Its hardest and most compact form is what gets used in jewelery as a gemstone. This is black, and is normally found in massive form as nodules, usually kidney shaped (reniform), sometimes known as kidney ore.
When crushed or powdered it becomes red, and its less compact forms are also red, streak tests are also red.
The compact black forms have specific gravities and hardness at the higher end of the range. The softer forms are used as red pigments, and as jeweler's rouge.

Misnomers

Because of its red streak, it is sometimes known in German as blutstein (bloodstone), but this term is better avoided because of confusion with bloodstone, a variety of chalcedony.

color

Gem quality hematite is black, although some describe it as blue-black.

Sources

One of the main sources is Cleator Moor in Cumbria, England, but it is also found in Elba, the Swiss alps, Germany, Scandinavia, and the USA.
It is carved or polished in Idar Oberstein, but much is now processed in places with lower labour costs.

Imitations

Hematite is sometimes used as beads to imitate black pearls. There are also imitations of haematite, at least one of which produces a red streak.

Hematite in Jewelery

Hematite is often carved as a cameo or sealstone, and is very commonly seen in gent's rings with a crude intaglio carving of a helmeted warrior's head. It is also used as a faceted stone when it resembles black diamond. Because it is opaque, only the top of the stone is faceted, the bottom of the stone is usually left flat.