igneous
Basalt
Extrusive Igneous Rock
AI-generated identification · may be incorrectHardness of 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure, and specific gravity around 2.8-3.0.
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Physical properties
Hardness of 6 on Mohs scale, dark gray to black color, dull luster, fine-grained aphanitic crystal structure, and specific gravity around 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of low-viscosity, magnesium- and iron-rich lava 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 stone wool insulation.
Geological facts
Basalt is the most common rock type on Earth's crust, underlying most ocean basins, and is also found abundantly on the Moon and Mars.
Field identification & locations
Identify in the field by its dark color, fine-grained texture, and heavy weight relative to its size; common globally in volcanic regions.
