Hematite
Hematite’s surface is a trap. Polished pieces look metallic — a dark steel gray shading to near-black, with a reflective sheen that reads as if it belongs with the metals rather than the minerals. But surface color is one of the least reliable ways to identify a mineral, because thin coatings, tarnish, and inclusions can all change what the eye sees. The test that actually identifies hematite is the streak test: scrape it across a piece of unglazed porcelain, and the powder it leaves behind is red-brown, not gray. That red-brown streak is where the name comes from — haima is Greek for blood — and it’s the standard diagnostic gemmologists and geologists use, because a mineral’s streak color is far more consistent than its surface appearance.
Chemically, hematite is iron oxide, Fe2O3, crystallizing in the trigonal system. It’s one of the most important iron ores on the planet — the primary source of the iron used in steel production for most of industrial history — which makes its use as a gem and ornamental material almost a side note to its economic role. As a gem material it’s typically cut and polished into cabochons, beads, and intaglios, prized for that dark metallic luster.
Hematite has an unusually high refractive index, in the range of 2.94 to 3.22 — higher than diamond’s 2.42. In practice this is rarely measured with a standard gemological refractometer, because hematite is opaque; refractive index measurements of that kind require light to pass through a material, so the figure is established through other optical methods rather than routine bench testing.
Major sources include Brazil, the United Kingdom (historically the Cumbria region), the United States, Canada, and Venezuela. Hematite is also notable for its role in mineral pigments — ochre and related iron-oxide pigments used in some of the earliest known art, including Paleolithic cave paintings, draw on the same red-brown iron oxide chemistry that defines hematite’s streak.
Hematite doesn’t appear on any of the historical or modern monthly birthstone lists, or on either zodiac system, tracked on this site — it’s included here as a standalone reference entry, the same way malachite is.
Gemmological properties
| Mohs hardness | 5–6.5 |
|---|---|
| Crystal system | Trigonal |
| Chemical formula | Fe2O3 |
| Refractive index | 2.94–3.22 |
| Color family | Black, Gray, Red |
| Variety of | — |
| Also known as | — |
| Origins | Brazil, United Kingdom, United States, Canada, Venezuela |
| Organic material | No |
Hematite looks metallic gray or black but leaves a distinctive red-brown streak when scraped — the diagnostic test that names it, from the Greek haima (blood). Its refractive index is unusually high, though it is rarely measured in practice because the material is opaque.
Frequently asked questions
- Why is hematite named for blood if it looks gray or black?
- The name comes from the Greek haima, meaning blood, and it refers to the streak, not the surface color. Hematite's polished or metallic-looking exterior is gray to black, but when scraped across an unglazed porcelain plate it leaves a reddish-brown powder — that streak, not the visible color, is the diagnostic test used to identify it.
- Is hematite the same as magnetite?
- No, though they're often confused. Both are iron oxide minerals and both occur in similar dark, metallic-looking forms, but hematite (Fe2O3) is only weakly magnetic at best, while magnetite (Fe3O4) is strongly magnetic. Much of the 'magnetic hematite' sold in jewelry is actually a synthetic ceramic material, not natural hematite at all.
- Is hematite a birthstone on any of the lists this site tracks?
- No. It doesn't appear on any of the historical, US, UK, or zodiac systems documented on this site — it's covered here as a standalone gemstone reference entry.