mineral
Magnetite (potentially Lodestone)
Magnetite (Iron(II,III) oxide, Fe3O4)
AI-generated identification · may be incorrectHardness: 5.5-6.5; Color: Black or dark grey; Luster: Metallic to submetallic; Crystal structure: Isometric (octahedron); Streak: Black; Magnetic: Strongly magnetic.
- Hardness
- 5
- Color
- Black or dark grey
- Luster
- Metallic to submetallic
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Physical properties
Hardness: 5.5-6.5; Color: Black or dark grey; Luster: Metallic to submetallic; Crystal structure: Isometric (octahedron); Streak: Black; Magnetic: Strongly magnetic.
Formation & geological history
Common in igneous rocks such as basalt and gabbro, as well as metamorphic rocks and some sedimentary deposits. It forms through crystallization from silica-rich magmas or by hydrothermal processes.
Uses & applications
The main ore of iron. Used in steel production, as a magnet in compasses historically, and as a heavy medium for coal separation.
Geological facts
Magnetite is the most magnetic of all the naturally-occurring minerals on Earth. Naturally magnetized pieces called lodestone were the first magnetic compasses used by humans.
Field identification & locations
Can be identified in the field using a handheld magnet or by its black streak. Often found in heavy mineral sands or as small grainy crystals in darker volcanic stones.
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Granite (Phaneritic intrusive igneous rock)
igneous
Calcite–fluorite mineral specimen with iron-oxide staining
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mineral