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), often vesicular or porphyritic, 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), often vesicular or porphyritic, 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, road aggregate, railroad ballast, and production of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins, and it is also found extensively on the Moon and Mars.
Field identification & locations
Identify in the field by its dark color and fine-grained texture. Commonly found in volcanic regions worldwide.
