igneous
Basalt
Extrusive igneous rock
AI-generated identification · may be incorrectHardness 6 on the Mohs scale, dark gray to black in color, fine-grained aphanitic texture, dull luster, composed primarily of plagioclase and pyroxene.
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Physical properties
Hardness 6 on the Mohs scale, dark gray to black in color, fine-grained aphanitic texture, dull luster, composed primarily of plagioclase and pyroxene.
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.
Uses & applications
Widely 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 crustal portions underlying the ocean basins and also forms massive volcanic features like the Giant's Causeway.
Field identification & locations
Identify by its dark color, fine-grained heavy texture, and magnetic susceptibility; commonly found in volcanic provinces and oceanic crust worldwide.
