igneous
Basalt Pebble
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, dark gray to black color, aphanitic (fine-grained) texture, dull to sub-metallic luster, specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black color, aphanitic (fine-grained) texture, dull to sub-metallic luster, specific gravity around 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the Earth's surface, often originating from volcanic eruptions.
Uses & applications
Used in construction as crushed aggregate, railroad ballast, road base, and in the production of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins, and it is also abundantly found on the Moon and Mars.
Field identification & locations
Identified by its dark color, fine-grained texture, and high density. Commonly found in riverbeds, beaches, and volcanic regions worldwide.
