igneous
Basalt
Basalt (silicate rock primarily plagioclase and pyroxene)
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. Most common rock in Earth's crust.
Uses & applications
Used widely in construction as decorative stone, floor tiles, and as an ingredient in concrete and asphalt for roads.
Geological facts
Basalt is the most common rock on the Earth's surface and also makes up most of the surface of the Moon, Mars, and Venus.
Field identification & locations
Identify by its dark color, heavy weight (relative to size), and fine-grained texture. Often found in volcanic regions and ocean floors.
