Magnetite
Magnetite also known as lodestone or loadstone, is a magnetic mineral form of iron (II, III) oxide, with chemical formula <math>\mathrm{Fe}_3\mathrm{O}_4<math> one of several iron oxides. Greyish black or iron in colour, with a metallic appearance a density of 5.1 and a hardness of 5.5 to 6.
Magnetite is the most magnetic of all the minerals on Earth, and these magnetic properties led to lodestones being used as an early form of magnetic compass.
Small grains of magnetite occur in almost all igneous and metamorphic rocks.
Magnetite is a valuable source of iron ore. It dissolves slowly in hydrochloric acid.
Large deposits of magnetite are found in Kiruna, Sweden, and in the Adirondack region of New York in the United States. Deposits are also found in Norway, Germany, Italy, Switzerland, South Africa, India, Mexico, and in Oregon, New Jersey, Pennsylvania, North Carolina, Virginia, New Mexico, Utah, and Colorado in the United States.
See also: Ferrite, Haematite, Magnesia, Maghemite
