mineral

Magnetite / Iron Ore

Magnetite (Fe3O4)

Hardness: 5.5-6.5 Mohs scale; Color: Black to silvery gray; Luster: Metallic to submetallic; Crystal structure: Isometric (octahedra); Cleavage: None (has parting); Specific Gravity: 5.1-5.2 (very heavy)

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

Identified April 12, 2026More mineral →

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Physical properties

Formation & geological history

Formed in igneous rocks through magmatic segregation, in metamorphic rocks via contact metamorphism, and in sedimentary rocks as heavy mineral sands. It is common in Precambrian banded iron formations.

Uses & applications

Primary ore of iron for steel manufacturing. Used as a heavy media in coal washing, an ingredient in high-density concrete, and as a historical pigment (magnetic sand).

Geological facts

Magnetite is the most magnetic mineral on Earth. When it is naturally magnetized as a lodestone, it was used by ancient civilizations as the first compasses.

Field identification & locations

Identify in the field using a strong magnet (it will be highly attracted) and its dark streak (the powder left on ceramic is black). Often found in dark volcanic rocks or river sands.