Mineral
Magnetita
Fe₃O₄ · Óxidos
Magnetite is an iron oxide with formula Fe₃O₄, recognisable by its black colour, metallic to submetallic lustre, and strong natural magnetism.
It is the major magnetic oxide of iron: Fe²⁺Fe³⁺₂O₄. It is one of the most important minerals for iron production. Before it was understood as a mineral, it was already technology: naturally magnetised pieces, the "lodestones", made the earliest compasses possible. It occurs in the granitic batholith of the Sierra de Guadarrama.
Etymology
Named after Magnesia, the Greek region long associated with naturally magnetic stones.