igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, dull to sub-withish luster, fine-grained aphanitic crystal structure.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, dull to sub-withish luster, fine-grained aphanitic crystal structure.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the surface of a planet or moon.
Uses & applications
Used extensively in construction as crushed aggregate for roads, 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 ocean basins and also forms much of the volcanic islands like Hawaii.
Field identification & locations
Identified by its dark, fine-grained appearance, often containing small vesicles from trapped gas bubbles. Found globally in volcanic provinces.
