mineral
Magnetite
Magnetite (Fe3O4)
Hardness: 5.5-6.5 (Mohs scale), Color: Black to dark gray, Luster: Metallic to submetallic, Crystal Structure: Isometric (often octahedral), Cleavage: None (parting may occur), Specific Gravity: 5.1-5.2
- Hardness
- 5
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Physical properties
Hardness: 5.5-6.5 (Mohs scale), Color: Black to dark gray, Luster: Metallic to submetallic, Crystal Structure: Isometric (often octahedral), Cleavage: None (parting may occur), Specific Gravity: 5.1-5.2
Formation & geological history
Formed in igneous, metamorphic, and sedimentary environments. It often crystallizes from cooling magma in mafic or ultramafic rocks or during contact metamorphism between igneous intrusions and limestone.
Uses & applications
Primary ore of iron, used in steel production, as a heavy media for coal separation, in toners, and as a magnetic contrast agent in medicine.
Geological facts
Magnetite is the most magnetic of all the naturally-occurring minerals on Earth. Naturally magnetized pieces are called lodestones and were used by ancient mariners as early compasses.
Field identification & locations
Identified in the field by its strong attraction to magnets and its black streak on a porcelain plate. Common locations include South Africa, Sweden, and the USA (New York, Pennsylvania).
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