igneous
Basalt
Extrusive Igneous Rock
Hardness: 6 on the Mohs scale, Color: Dark gray to black, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic (fine-grained) with sometimes vesicular or porphyritic textures, Specific gravity: 2.8 - 3.0
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Physical properties
Hardness: 6 on the Mohs scale, Color: Dark gray to black, Luster: Dull to sub-vitreous, Crystal structure: Aphanitic (fine-grained) with sometimes vesicular or porphyritic textures, Specific gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity, iron- and magnesium-rich lava exposed at or very near the surface of a planet or moon.
Uses & applications
Used in construction as crushed stone for road bases, concrete aggregate, railroad ballast, and in the manufacturing of stone wool insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the ocean basins, and it is also commonly found on the Moon and Mars.
Field identification & locations
Identify by its dark, fine-grained appearance, high density, and occasional presence of vesicles or small mineral phenocrysts like olivine or plagioclase.
