igneous
Basalt Pebble
Extrusive igneous rock
AI-generated identification · may be incorrectMohs hardness of 6; dark gray to black color; fine-grained aphanitic texture; dull to sub-metallic luster.
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Physical properties
Mohs hardness of 6; dark gray to black color; fine-grained aphanitic texture; 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
Used widely in construction as crushed 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.
Field identification & locations
Easily identified by its dark, dense, and fine-grained nature, commonly found in riverbeds and beaches as smooth pebbles.
