igneous
Basalt
Extrusive Igneous Rock
Hardness: 6 on the Mohs scale; Color: Dark grey to black; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic (fine-grained), often containing microscopic crystals or volcanic glass; Specific gravity: 2.8 - 3.0
- Hardness
- 6 on the Mohs scale
- Color
- Dark grey to black
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 6 on the Mohs scale; Color: Dark grey to black; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic (fine-grained), often containing microscopic crystals or volcanic glass; Specific gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a planet or moon. Typically forms via volcanic eruptions.
Uses & applications
Used in construction, aggregate for road bases, production of rock wool insulation, and manufacturing of tiles and slabs.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins and is also found abundantly on the Moon and Mars.
Field identification & locations
Identified by its dark color, fine-grained texture, and heavy weight relative to its size. Found globally in volcanic provinces and oceanic crusts.
