igneous
Basalt
Basalt
Hardness: 6.0; Color: dark grey to black; Luster: dull to sub-metallic; Crystal structure: fine-grained (aphanitic); Cleavage: none; Specific gravity: 2.8 - 3.0
- Hardness
- 6
- Color
- dark grey to black
- Luster
- dull to sub-metallic
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Physical properties
Hardness: 6.0; Color: dark grey to black; Luster: dull to sub-metallic; Crystal structure: fine-grained (aphanitic); Cleavage: none; Specific gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon. Often found in oceanic crust and volcanic regions.
Uses & applications
Used primarily in construction as aggregate for concrete and asphalt, for road base, and as floor tiles or dimension stone.
Geological facts
Basalt is the most common rock type in the Earth's crust and covers most of the ocean floor. It is also found on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (density), and lack of visible crystals to the naked eye. Found worldwide in volcanic areas like Hawaii, Iceland, and the Pacific Northwest.
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