igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull to sub-to-submetallic luster, fine-grained aphanitic crystal structure.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, dull to sub-to-submetallic luster, fine-grained aphanitic crystal structure.
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in iron and magnesium exposed at or very near the surface of a planet or moon.
Uses & applications
Commonly used in construction as crushed aggregate for roads, railroad ballast, and in the production of rock wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins and also forms massive geological structures like the Giant's Causeway.
Field identification & locations
Identify by its dark, dense, fine-grained appearance; found worldwide in volcanic provinces and oceanic crusts.
