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 with microscopic crystals, and dull to sub-vitreous luster.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, aphanitic texture with microscopic crystals, and dull to sub-vitreous luster.
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 widely in construction aggregates, road base, asphalt production, and occasionally as landscaping stones.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms dramatic columnar jointing formations like the Giant's Causeway.
Field identification & locations
Identified by its dense, fine-grained dark appearance and common occurrence in stream beds and beaches; easily found worldwide.
