Loadstone

Loadstone, hard black mineral (Fe₃0₄) with magnetic properties, also called lodestone and magnetite. It is found in the form of rocks, crystals, and sand in Siberia, South Africa, and parts of Italy and the United States. Loadstone was used as a precursor to the compass, when ancient Europeans discovered that if an oblong piece of it was suspended from a string, it would point north and south.

See also: Magnetism.