igneous
Basalt Pebble
Aphanitic 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, no visible cleavage, specific gravity around 2.9.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull luster, microcrystalline to cryptocrystalline structure, no visible cleavage, specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity, mafic lava flows at or near the Earth's surface.
Uses & applications
Used in construction, aggregate for concrete, road base, and crushed stone.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and also forms extensive volcanic provinces on land.
Field identification & locations
Found globally in volcanic regions, riverbeds, and beaches where wave action smooths the dense rock into pebbles.
