igneous
Basalt Fragment
Extrusive Igneous Rock
Hardness of 6 on Mohs scale, dark gray to black color, aphanitic (fine-grained) texture, dull to sub-vitreous luster, specific gravity around 2.8 to 3.0
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, aphanitic (fine-grained) texture, dull to sub-vitreous luster, specific gravity around 2.8 to 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, railroad ballast, and in the production of rock wool insulation
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins, and it is also abundantly found on the Moon, Mars, and Venus
Field identification & locations
Easily identified by its dark, fine-grained appearance, often vesicular due to trapped gas bubbles, and found in volcanic regions worldwide
