igneous
Basalt
Extrusive Igneous Rock
Hardness: 6 on Mohs scale, Color: Dark grey to black, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic (fine-grained), Cleavage: None, Specific gravity: 2.8-3.0
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Physical properties
Hardness: 6 on Mohs scale, Color: Dark grey to black, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic (fine-grained), Cleavage: None, 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.
Uses & applications
Used in construction, aggregate for roads, making rock wool insulation, and occasionally in stone carving.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins, and is also found extensively on the Moon and Mars.
Field identification & locations
Identify by its dark, fine-grained appearance, often vesicular due to trapped gas bubbles. Found worldwide in volcanic provinces and oceanic ridges.
