mineral
Magnetite / Lodestone
Magnetite (Fe3O4)
Mohs hardness: 5.5-6.5; Color: Dark grey to black, metallic sub-shiny; Luster: Metallic to sub-metallic; Streak: Black; Specific Gravity: ~5.18; Crystal System: Isometric (octahedral when crystallized). Strongly magnetic.
- Hardness
- 5
- Color
- Dark grey to black, metallic sub-shiny
- Luster
- Metallic to sub-metallic
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Physical properties
Mohs hardness: 5.5-6.5; Color: Dark grey to black, metallic sub-shiny; Luster: Metallic to sub-metallic; Streak: Black; Specific Gravity: ~5.18; Crystal System: Isometric (octahedral when crystallized). Strongly magnetic.
Formation & geological history
Forms in igneous, metamorphic, and sedimentary rocks as an accessory mineral or concentrated ore deposit, often through magmatic segregation or hydrothermal replacement.
Uses & applications
Primary ore of iron; used in heavy media separation, water filtration, industrial pigments, and as natural magnetic specimens (lodestone) for education and collecting.
Geological facts
Magnetite is the most magnetic naturally-occurring mineral on Earth. Naturally magnetized pieces called lodestones were used to create the earliest magnetic compasses in ancient history.
Field identification & locations
Identified in the field by its strong attraction to magnets, heavy feel (high specific gravity), black streak, and dark metallic-to-dull surface appearance.
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