igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, aphanitic texture with microscopic crystals, and dull to sub-metallic luster.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, aphanitic texture with microscopic crystals, and dull to sub-metallic luster.
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 for crushed stone, road 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 famous formations like the Giant's Causeway.
Field identification & locations
Identify by its dark, fine-grained matrix and vesicular texture caused by trapped gas bubbles; common globally in volcanic provinces.
