igneous
Basalt
Extrusive Igneous Rock
Hardness of 6 on Mohs scale, dark gray to black color, aphanitic (fine-grained) texture, dull luster, specific gravity of 2.8-3.0
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, aphanitic (fine-grained) texture, dull luster, specific gravity of 2.8-3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the surface of a planet or moon
Uses & applications
Used in construction as crushed stone for road bases, concrete aggregate, and railroad ballast, as well as in the manufacturing of rock wool insulation
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins and is also extensively found on the Moon and Mars
Field identification & locations
Easily identified by its dark, fine-grained appearance, often vesicular due to trapped gas bubbles; found globally in volcanic regions and flood basalt provinces
