mineral

Magnetite (Lodestone)

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal structure: Isometric (octahedral); Cleavage: None; Specific gravity: 5.1-5.2; Notable property: Strongly magnetic.

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

Identified July 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous rocks as a primary accessory mineral, in metamorphic rocks through regional metamorphism, and in sedimentary rocks as heavy mineral sands. Occurs in contact metamorphic zones and hydrothermal veins.

Uses & applications

Major ore of iron for steel manufacturing; used as a heavy medium for coal washing, in fertilizers, as a toner in photocopiers, and as a collector's specimen if naturally magnetized (lodestone).

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 primitive magnetic compasses in ancient history.

Field identification & locations

Identify by its black streak, high density, and strong attraction to magnets. Found globally, with notable deposits in Sweden, South Africa, and the USA (Lake Superior region). Look for heavy, dark, metallic grains in sand or massive ore bodies.