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, no prominent cleavage, and a 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, no prominent cleavage, and a specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava flows on Earth's surface, typically originating in volcanic environments.
Uses & applications
Used in construction as crushed aggregate, railroad ballast, and dimension stone.
Geological facts
Basalt is the most common rock type on Earth's oceanic crust and is also abundantly found on the surfaces of the Moon and Mars.
Field identification & locations
Identified in the field by its fine-grained dark appearance and rounded river-worn shape; commonly found in stream beds and beaches.
