igneous
Basalt
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, dark gray to black in color, fine-grained aphanitic texture, dull to submetallic luster, specific gravity around 2.8 - 3.0
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Physical properties
Hardness of 6 on the Mohs scale, dark gray to black in color, fine-grained aphanitic texture, dull to submetallic luster, specific gravity around 2.8 - 3.0
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, road base, railroad ballast, and in the production of stone wool insulation
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins and also makes up extensive volcanic formations on the Moon and Mars
Field identification & locations
Identified by its dark color and fine-grained texture where individual crystals are generally not visible to the naked eye; commonly found in volcanic regions worldwide
