Magnetite, a ferrimagnetic mineral with chemical formula Fe3O4, one of several iron oxides, is one of the more common meteor-wrongs. Magnetite displays a black exterior and magnetic properties.

  magnetite

Magnetite can be a found in a meteorite's crust. When a meteor enters the earth's atmosphere the rock's surface is ablated by ultra high temperatures. Before it hits the ground, the molten surface solidifies into a thin glassy coating, called fusion crust. Crystals of magnetite color the thin fusion crust black. (Magnetite streaks black - see photo below)

  lodestone

A piece of intensely magnetic magnetite was used as an early form of magnetic compass. Iron, steel and ordinary magnetite are attracted to a magnetic field, including the Earth's magnetic field. Only magnetite with a particular crystalline structure, lodestone, can act as a natural magnet and attract and magnetize iron. The name "magnet" comes from lodestones found in a place called Magnesia.
  wikipedia

The rounded shape and black color are often mistaken for meteorites. (See Tucson Mtns Magnetite Photos) Magnetite is often sold on eBay as 'meteorites' (photos below and More Photos Here):



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