igneous
Basalt Pebble
Aphanitic mafic extrusive igneous rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull luster, microcrystalline to cryptocrystalline structure, and high density.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull luster, microcrystalline to cryptocrystalline structure, and high density.
Formation & geological history
Formed from the rapid cooling of magnesium- and iron-rich lava exposed at or near the surface of a planet or moon.
Uses & applications
Used widely in construction as crushed aggregate, railroad ballast, and dimension stone for buildings.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins.
Field identification & locations
Found abundantly in volcanic regions and riverbeds worldwide as smoothed pebbles; identified by its dark color and fine-grained texture.
