igneous
Basalt Pebble
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, sub-metallic to dull luster, fine-grained aphanitic crystal structure, and a specific gravity of 2.8 to 3.0.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, sub-metallic to dull luster, fine-grained aphanitic crystal structure, and a specific gravity of 2.8 to 3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or near the Earth's surface, often shaped into a smooth pebble by water action in rivers or shorelines.
Uses & applications
Used widely in construction as crushed aggregate, railroad ballast, dimension stone, and occasionally in polished landscape decor.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also makes up extensive volcanic formations on the Moon and Mars.
Field identification & locations
Identified by its dark color, heavy weight, and dense fine-grained matrix; commonly found in riverbeds, beaches, and volcanic regions worldwide.
