Hematite is a variety of iron oxide (Fe2O3), a mineral mined as one of the main ores of iron. It is also used industrially as a red pigment in paint, and in polishing compounds. The specimen shown here has a bulbous appearance, also referred to as botryoidal (grapelike), which in mining practice is referred to as kidney ore. In nature its surface is always coloured a dull yellowish to red-brown; the glossy black surface here seen is thanks to polishing. Specimen is from the Geevor mine near St Just, Cornwall, UK. Actual width is 190 mm.