igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on Mohs scale, dark gray to black color, aphanitic to porphyritic texture, dull luster.
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Physical properties
Hardness 6 on Mohs scale, dark gray to black color, aphanitic to porphyritic texture, dull 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
Commonly used in construction as crushed stone, railroad ballast, and aggregate in concrete.
Geological facts
Basalt is the most common rock type in the Earth's crustal portions underlying the world's ocean basins.
Field identification & locations
Identify by its dense, dark, fine-grained matrix and smooth water-worn surface in riverbeds.
