mineral

Magnetite

Magnetite (Fe3O4)

Hardness: 5.5-6.5 (Mohs), Color: Black to brownish black, Luster: Metallic to submetallic, Crystal Structure: Isometric (typically octahedral), Cleavage: None/Indistinct, Specific Gravity: 5.1-5.2

Hardness: 5

Identified February 18, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5 (Mohs), Color: Black to brownish black, Luster: Metallic to submetallic, Crystal Structure: Isometric (typically octahedral), Cleavage: None/Indistinct, Specific Gravity: 5.1-5.2

Formation & geological history

Formed in high-temperature igneous and metamorphic environments, and as a heavy mineral in some sedimentary deposits. It is often found in contact metamorphic zones and as a primary mineral in basic igneous rocks like basalt and gabbro.

Uses & applications

Primary ore of iron; used in heavy media separation, water filtration, and in the production of magnetic pigments and high-density concrete.

Geological facts

Magnetite is the most magnetic of all mineral species. Some specimens, known as lodestones, are naturally magnetized and were used by ancient civilizations as the first compasses.

Field identification & locations

Identify in the field using a handheld magnet; it will be strongly attracted. Look for black, metallic, heavy grains in river sand or as integrated crystals in dark igneous rocks. Found globally, notably in Sweden, Australia, and the USA.