mineral

Magnetite with Quartz

Magnetite (Fe3O4)

Hardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal structure: Isometric/Octahedral; Cleavage: None; Specific Gravity: 5.17-5.18

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

Identified June 27, 2026More mineral →

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Physical properties

Hardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal structure: Isometric/Octahedral; Cleavage: None; Specific Gravity: 5.17-5.18

Formation & geological history

Commonly forms in igneous rocks through magmatic segregation, in metamorphic rocks through regional or contact metamorphism, and in sedimentary rocks as heavy mineral sands.

Uses & applications

Primary ore of iron; used in heavy media separation, as a pigment (mars black), and occasionally in jewelry as 'loadstone' or magnetic beads.

Geological facts

Magnetite is the most magnetic of all the naturally-occurring minerals on Earth. It was used by ancient civilizations as the first compasses (lodestones).

Field identification & locations

Identify in the field by its strong attraction to magnets and its black streak on a porcelain plate. Often found in iron-rich sands or as inclusions in granite and gneiss.