igneous
Basalt Pebble
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull luster, aphanitic crystal structure, and high 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, aphanitic crystal structure, and high specific gravity around 2.9.
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 in construction aggregates, road base, riprap, and occasionally in stone masonry.
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
Identify by its dark, fine-grained appearance and heavy weight; commonly found in riverbeds and beaches as smooth, water-worn pebbles.
