igneous
Crushed Basalt / Diabase Gravel
Basalt / Mafic Igneous Rock
Hardness: 6-7 Mohs. Color: Dark gray to bluish-black. Luster: Dull to sub-vitreous. Structure: Fine-grained (aphanitic) to microcrystalline. Cleavage: None (conchoidal to irregular fracture).
- Hardness
- 6-7 Mohs
- Color
- Dark gray to bluish-black
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 6-7 Mohs. Color: Dark gray to bluish-black. Luster: Dull to sub-vitreous. Structure: Fine-grained (aphanitic) to microcrystalline. Cleavage: None (conchoidal to irregular fracture).
Formation & geological history
Formed from the rapid cooling of mafic lava or shallow intrusive magma rich in magnesium and iron. Abundant in volcanic provinces, oceanic crusts, and rift zones globally.
Uses & applications
Widely used in civil engineering, road construction base, concrete aggregate, railway ballast, and decorative landscaping gravel.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floors. It also covers large areas of the Moon, Mars, and Venus.
Field identification & locations
Identified by its fine grain size, high density, and dark charcoal or bluish-gray color. Very common in crushed gravel landscaping and driveway gravel.
