A black mineral form of iron oxide crystallizing in the cubic system. It is a mixed iron(II)-iron(III) oxide, Fe3O4, and is one of the major ores of iron. It is strongly magnetic and some varieties, known as lodestone, are natural magnets; these were used as compasses in the ancient world. Magnetite is widely distributed and occurs as an accessory mineral in almost all igneous and metamorphic rocks. The largest deposits of the mineral occur in N Sweden.
Subjects: Earth Sciences and Geography — Chemistry.