mineral
Magnetite / Iron Ore
Magnetite (Fe3O4)
AI-generated identification · may be incorrectHardness: 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
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Physical properties
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)
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.
