mineral

Magnetite (Iron Ore)

Magnetite (Fe3O4)

Hardness: 5.5–6.5 Mohs scale; Color: Black to dark gray; Luster: Metallic to sub-metallic; Crystal structure: Isometric (often octahedral); Cleavage: None/Indistinct; Specific Gravity: 5.17–5.18 (very heavy); Magnetic: Naturally attracted to magnets.

Hardness: 5
Color: Black to dark gray
Luster: Metallic to sub-metallic

Identified March 14, 2026More mineral →

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Physical properties

Formation & geological history

Forms in igneous, metamorphic, and sedimentary environments. It is often found as a primary mineral in igneous rocks like basalt or gabbro, but can also form through contact metamorphism or as a heavy mineral sand in sedimentary deposits. It has been forming throughout Earth's geological history, from the Archean to the present day.

Uses & applications

Primary ore of iron for steel production; used in toner for laser printers, magnetic recording media, and as a catalyst in the Haber process for making ammonia. Some highly magnetic varieties (lodestone) are used for scientific education and metaphysical collecting.

Geological facts

Naturally magnetized magnetite is known as 'lodestone' and was used as the first primitive compass. It is names after the Magnesia region in Greece. Large deposits in Kiruna, Sweden, are among the world's most significant sources.

Field identification & locations

Identify in the field by its black streak (on a ceramic plate), high density (it feels heavy for its size), and its strong attraction to a hand magnet. Found worldwide, notably in the Great Lakes region (USA), Sweden, Russia, and South Africa.