mineral

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Hardness: 5.5 to 6.5 on the Mohs scale. Color: Black to brownish-black. Luster: Metallic to submetallic. Crystal structure: Isometric (often octahedral). Cleavage: None (exhibits octahedral parting). Specific Gravity: 5.17 to 5.18. Key feature: Strongly magnetic.

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

Identified January 2, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous, metamorphic, and sedimentary environments. It frequently occurs as an accessory mineral in igneous rocks like granite and basalt, or in massive layers within banded iron formations (BIFs) dating back to the Archean and Proterozoic eons (2.5 to 3.8 billion years ago).

Uses & applications

Primary ore of iron used for steel production. Used as a heavy media for coal washing, as a pigment (mars black) in paints and ceramics, and in magnetic recording media. Rarely used as a gemstone in the form of 'lodestone' for collectors.

Geological facts

Magnetite is the most magnetic mineral on Earth. In its naturally magnetized form, it is called Lodestone; these were used by ancient civilizations as the first compasses. Grains of magnetite have even been found in the brains of some animals, helping them navigate using Earth's magnetic field.

Field identification & locations

Identify in the field using a strong magnet; the specimen will be strongly attracted to it. It leaves a black streak when rubbed on a porcelain plate. Common locations include the Iron Range in Minnesota (USA), Kiruna (Sweden), and the Ural Mountains (Russia). Look for heavy, dark, metallic rocks in areas with known volcanic or metamorphic history.