mineral
Magnetite (Iron Ore)
Magnetite (Fe3O4)
Hardness: 5.5-6.5 (Mohs), Color: Black to dark brown/rusty, Luster: Metallic to submetallic, Crystal Structure: Isometric (often octahedral), Cleavage: None/Indistinct, Specific Gravity: 5.1-5.2 (very heavy)
- Hardness
- 5
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Physical properties
Hardness: 5.5-6.5 (Mohs), Color: Black to dark brown/rusty, Luster: Metallic to submetallic, Crystal Structure: Isometric (often octahedral), Cleavage: None/Indistinct, Specific Gravity: 5.1-5.2 (very heavy)
Formation & geological history
Formed in igneous, metamorphic, and some sedimentary environments. It frequently occurs as an accessory mineral in granite and basalt or in hydrothermal veins and contact metamorphic zones.
Uses & applications
Primary ore of iron; used in the manufacturing of steel, as a heavy aggregate in concrete, as a pigment, and in industrial separation processes (dense media separation).
Geological facts
Magnetite is the most magnetic of all the naturally occurring minerals on Earth. Naturally magnetized pieces called lodestones were used by ancient mariners to create the first compasses.
Field identification & locations
Identify in the field by its strong attraction to a magnet and its black streak. It is commonly found globally, particularly in Sweden, South Africa, and the USA (Appalachians and Iron Range). collectors look for sharp octahedral crystal forms.
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Metamorphic
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metamorphic
Gypsum (variety Selenite or Alabaster)
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Mineral
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Nephrite
Mineral/Rock
Granite
Granite (Phaneritic intrusive igneous rock)
igneous