mineral
Black Sand (Magnetite Sand)
Magnetite (Fe3O4)
AI-generated identification · may be incorrectHardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal Structure: Isometric; Specific Gravity: Approx. 5.17; strongly magnetic.
- Hardness
- 5
- Color
- Black to dark gray
- Luster
- Metallic to submetallic
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Physical properties
Hardness: 5.5-6.5; Color: Black to dark gray; Luster: Metallic to submetallic; Crystal Structure: Isometric; Specific Gravity: Approx. 5.17; strongly magnetic.
Formation & geological history
Formed by the weathering of igneous or metamorphic rocks containing iron-bearing minerals. The heavy minerals are concentrated by water action (placer deposits) on beaches or riverbeds.
Uses & applications
Used as a major ore of iron, in heavy media separation, as a pigment, and occasionally as a specimen for educational or decorative sand art.
Geological facts
Magnetite is one of the most magnetic natural minerals on Earth. It was used by ancient sailors as a primitive compass because it would align with the Earth's magnetic poles.
Field identification & locations
Can be identified in the field using a simple hand magnet; the sand grains will readily cling to the magnet. Commonly found on beaches near volcanic activity or in heavy mineral patches on riverbanks.
