mineral

Magnetite

Magnetite (Iron(II,III) oxide, Fe3O4)

Hardness: 5.5 - 6.5 Mohs. Color: Black to silvery-gray. Luster: Metallic to submetallic. Crystal Structure: Isometric (octahedron). Cleavage: None (parting sometimes visible). Specific Gravity: 5.17 - 5.18.

Hardness: 5
Color: Black to silvery-gray
Luster: Metallic to submetallic

Identified March 19, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous, metamorphic, and sedimentary environments. Often occurs as an accessory mineral in igneous rocks like basalt or gabbro, or through hydrothermal replacement in contact metamorphic zones (skarns). It is one of the oldest minerals on Earth, found in formations billions of years old.

Uses & applications

Primary ore of iron; used in heavy media separation, water filtration, and high-density concrete. Occasionally used as a gemstone (loadstone) or in magnetic jewelry and for industrial magnets.

Geological facts

Magnetite is the most magnetic of all naturally occurring minerals on Earth. Naturally magnetized pieces called 'lodestones' were used by ancient civilizations as the first primitive compasses because they would align with the Earth's magnetic field.

Field identification & locations

Identify in the field using a strong magnet or a streak test (produces a black streak). It is commonly found in beach sands (black sands), iron mines, and volcanic terrain. Collectors look for sharp, well-defined octahedral crystals like the ones shown.