mineral
Magnetite
Fe3O4 (Iron(II,III) oxide)
Hardness: 5.5-6.5 on the Mohs scale; Color: Black to silvery-dark gray; Luster: Metallic to submetallic; Crystal Structure: Isometric (octahedral or dodecahedral); Cleavage: None, exhibits parting; Specific Gravity: 5.15 - 5.18; Highly magnetic.
- Hardness
- 5
- Color
- Black to silvery-dark gray
- Luster
- Metallic to submetallic
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Physical properties
Hardness: 5.5-6.5 on the Mohs scale; Color: Black to silvery-dark gray; Luster: Metallic to submetallic; Crystal Structure: Isometric (octahedral or dodecahedral); Cleavage: None, exhibits parting; Specific Gravity: 5.15 - 5.18; Highly magnetic.
Formation & geological history
Forms in igneous rocks as an accessory mineral, in metamorphic rocks through the alteration of other iron-rich minerals, and in sedimentary environments as detrital grains or banded iron formations.
Uses & applications
Primary ore of iron; used in heavy media separation, coal washing, water filtration, and in the manufacturing of magnets.
Geological facts
Magnetite is the most magnetic naturally occurring mineral on Earth. Sometimes natural magnets, known as lodestones, are composed of magnetized magnetite.
Field identification & locations
Easily identified by its strong magnetism, black streak, and high density. Found worldwide in beach sands, igneous intrusions, and metamorphic iron formations.
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Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
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Septarian Pebble
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Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
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Schist
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