mineral

Magnetite (Small Granule)

Magnetite (Fe3O4)

Hardness: 5.5-6.5 Mohs; Color: Black to brownish-black; Luster: Metallic to submetallic; Crystal Structure: Isometric; Cleavage: None; Specific Gravity: 5.1-5.2

Hardness: 5
Color: Black to brownish-black
Luster: Metallic to submetallic

Identified May 20, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 5.5-6.5 Mohs; Color: Black to brownish-black; Luster: Metallic to submetallic; Crystal Structure: Isometric; Cleavage: None; Specific Gravity: 5.1-5.2

Formation & geological history

Formed in igneous, metamorphic, and some sedimentary environments. It frequently crystallizes from cooling magma as an accessory mineral or forms through metamorphic processes in iron-rich sediments.

Uses & applications

The primary ore of iron; used in heavy media separation, as a pigment in paints (Mars Black), and in the production of magnets and electronics.

Geological facts

Magnetite is the most magnetic of all the naturally-occurring minerals on Earth. Pieces like 'lodestone' were used by ancient civilizations to create the first magnetic compasses.

Field identification & locations

Easily identified in the field because it is strongly attracted to a magnet. It often appears as heavy, dark, metallic sand or octahedron crystals in streambeds or within volcanic rocks.