igneous
Basalt
Extrusive mafic igneous rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull luster, aphanitic (fine-grained) crystal structure, specific gravity around 2.9.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, dull luster, aphanitic (fine-grained) crystal structure, specific gravity around 2.9.
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the Earth's surface, dating across various geological eras.
Uses & applications
Widely used in construction, aggregate for roads, railroad ballast, and sometimes in dimension stone or basalt fiber production.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and forms famous formations like the Giant's Causeway.
Field identification & locations
Identify by its dark, fine-grained appearance and heavy weight. Commonly found globally in volcanic regions and oceanic crust.
