igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure.
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Physical properties
Hardness 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 basaltic lava exposed at or very near the Earth's surface.
Uses & applications
Used extensively in construction as crushed stone for road bases, concrete aggregate, 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 lunar maria.
Field identification & locations
Identify in the field by its dark, dense, fine-grained matrix, often containing small visible vesicles or mineral phenocrysts.
