igneous
Basalt
Basalt
Hardness: 6; Color: Dark grey to black; Luster: Dull to sub-metallic; Structure: Fine-grained (aphanitic); 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; Color: Dark grey to black; Luster: Dull to sub-metallic; Structure: Fine-grained (aphanitic); 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.
Uses & applications
Used primarily in construction for aggregate, road base, and concrete; also used as a dimension stone for floor tiles and landscaping.
Geological facts
Basalt is the most common rock on Earth's surface and makes up most of the ocean floor. It is also found extensively on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight for its size, and absence of visible crystals. Common in volcanic regions like Hawaii or the Pacific Northwest.
