igneous
Basalt Pebble
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, aphanitic texture, and specific gravity around 2.9.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, aphanitic texture, and specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity, iron- and magnesium-rich lava exposed at or very near the Earth's surface.
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 and forming major volcanic features.
Field identification & locations
Identify by its dark color, fine-grained texture requiring a lens to see crystals, and common occurrence as river or beach pebbles.
