mineral

Magnetite

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Iron-black to dark grey; Luster: Metallic to submetallic; Crystal Structure: Isometric/Octahedral; Cleavage: None (parting on {111}); Specific Gravity: 5.1-5.2.

Hardness: 5
Color: Iron-black to dark grey
Luster: Metallic to submetallic

Identified June 30, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5; Color: Iron-black to dark grey; Luster: Metallic to submetallic; Crystal Structure: Isometric/Octahedral; Cleavage: None (parting on {111}); Specific Gravity: 5.1-5.2.

Formation & geological history

Formed in igneous, metamorphic, and sedimentary environments. Often found as an accessory mineral in igneous rocks like basalt and gabbro, or in banded iron formations. Some deposits are billions of years old.

Uses & applications

Primary ore of iron; used in heavy media separation, as a pigment (ochre), and in the manufacture of steel and magnetic recording media.

Geological facts

Magnetite is the most magnetic of all the naturally-occurring minerals on Earth. Naturally magnetized pieces called lodestones were used as the first magnetic compasses.

Field identification & locations

Identified in the field by its strong attraction to magnets and its black streak. Often found in heavy mineral sands or as small black grains in crystalline rocks. It is a common 'black sand' component.