igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava exposed at or very near the Earth's surface.
Uses & applications
Widely used in construction as crushed aggregate, railroad ballast, and dimension stone.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the ocean basins and forms much of the moon's maria.
Field identification & locations
Identify by its dark, dense, fine-grained matrix, often found in volcanic regions and ancient lava flows worldwide.
