Hematite, an iron oxide, derives its name from the Greek word for blood, since it is red when sliced thinly or powdered. Hematite is one of very few gemstones with a metallic luster. Hematite is always opaque and is typically a blackish grey. When highly polished it can sometimes look like silver. Hematite is a remarkably dense material, with a specific gravity much higher than corundum or zircon.