magnetita

Magnetite is an iron oxide mineral with the chemical formula Fe3O4. It is one of the main sources of iron and is renowned for its strong magnetic properties, historically known as lodestone, the natural magnet used in early compasses.

Magnetite crystallizes in the inverse spinel structure and contains both Fe2+ and Fe3+ ions. Its ferrimagnetism arises from the partial alignment of magnetic moments on different sublattices, producing a net magnetization. The Curie temperature is about 858 kelvin, above which it loses its permanent magnetism.

Magnetite occurs in a variety of geological settings. It is found in igneous and metamorphic rocks as well as some sedimentary deposits, forming during magmatic crystallization and through redox processes in rocks. It is also common in placer deposits and can be present in meteorites.

As an iron ore, magnetite is mined and processed to extract iron. Its magnetic properties have practical applications in magnetic separation and various magnetic devices. In nanotechnology, magnetite nanoparticles are used in biomedical applications such as magnetic resonance imaging (MRI) contrast agents, drug delivery, and hyperthermia therapies, among others.

The name magnetite derives from the Greek magnetis lithos, meaning “magnetic rock.”