igneous
Basalt Pebble
Aphanitic Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on the Mohs scale, dark gray to black color, dull to sub-vitreous luster, microcrystalline or cryptocrystalline structure, no distinct cleavage, specific gravity of 2.8-3.0.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, dull to sub-vitreous luster, microcrystalline or cryptocrystalline structure, no distinct cleavage, specific gravity of 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of mafic lava exposed at or very near the surface of a planet or moon. Geological age varies widely from recent volcanic flows to billions of years old.
Uses & applications
Used in construction, as crushed stone for road bases, concrete aggregate, railroad ballast, and sometimes in landscaping and decorative stones.
Geological facts
Basalt is the most common rock type in the Earth's oceanic crust and is also found abundantly on the Moon, Mars, and Venus.
Field identification & locations
Found worldwide in volcanic regions, near ancient lava flows, and along riverbeds or coastlines where water has smoothed them into pebbles. Identify by its dark color, fine-grained texture, and high density.
