igneous
Basalt
Extrusive Igneous Rock
Hardness of 6 on the Mohs scale, typically dark gray to black in color, dull to sub-mettalic luster, fine-grained (aphanitic) crystal structure, specific gravity around 2.8 - 3.0
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Physical properties
Hardness of 6 on the Mohs scale, typically dark gray to black in color, dull to sub-mettalic luster, fine-grained (aphanitic) crystal structure, specific gravity around 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity lava rich in magnesium and iron exposed at or very near the surface of a rocky planet or moon
Uses & applications
Commonly used in construction, aggregate for roads, making stone wool insulation, and occasionally as dimension stone
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's oceans, and it is also abundantly found on the Moon and Mars
Field identification & locations
Identified by its dark color, fine-grained texture, and heavy weight relative to its size; found globally in volcanic regions and oceanic crusts
