igneous
Basalt
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, typically dark gray to black in color, dull to sub-with a fine-grained aphanitic texture, specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color, dull to sub-with a fine-grained aphanitic texture, specific gravity around 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a planet or moon.
Uses & applications
Used extensively in construction, aggregate for roads, making railroad ballast, 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 oceans and also forms major geological features like the Giant's Causeway in Northern Ireland.
Field identification & locations
Identified by its dark color, fine-grained texture, and heavy weight relative to its size. Commonly found in volcanic regions worldwide.
