igneous
Basalt
Mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, typically dark gray to black in color, with a dull to sub-withish luster and an aphanitic or fine-grained crystalline structure.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color, with a dull to sub-withish luster and an aphanitic or fine-grained crystalline 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
Widely used 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 crustal portions underlying the ocean basins and forms massive geological formations like the Columbia River Flood Basalts.
Field identification & locations
Identify by its dark, fine-grained groundmass, often with visible small crystals of plagioclase or olivine; commonly found in volcanic regions worldwide.
