mineral

Magnetite

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal structure: Isometric (octahedral); Cleavage: None (has parting); Specific gravity: 5.1-5.2

Hardness: 5
Color: Black to dark gray
Luster: Metallic to submetallic

Identified June 27, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal structure: Isometric (octahedral); Cleavage: None (has parting); Specific gravity: 5.1-5.2

Formation & geological history

Formed in igneous rocks like basalt and gabbro through magmatic segregation, as well as in metamorphic rocks and banded iron formations. Can also be found as heavy sand in sedimentary deposits.

Uses & applications

Primary ore of iron; used in heavy media separation, as a pigment in paints (Mars Black), and for industrial magnets.

Geological facts

Magnetite is the most magnetic naturally occurring mineral on Earth. Small grains of magnetite are found in the brains of many animals to help them navigate via the Earth's magnetic field.

Field identification & locations

The easiest field identification is its strong attraction to a magnet. Look for high density and a black streak when rubbed against a porcelain plate. Common in black sand beaches and near volcanic areas.