igneous
Basalt
Basalt
Hardness: 6 (Mohs scale), Color: black or dark grey, Luster: dull to sub-microscopic, Structure: fine-grained (aphanitic), Specific Gravity: 2.8 - 3.0
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Physical properties
Hardness: 6 (Mohs scale), Color: black or dark grey, Luster: dull to sub-microscopic, Structure: fine-grained (aphanitic), Specific Gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava exposed at or very near the surface of a terrestrial planet or a moon.
Uses & applications
Used in construction (crushed stone, asphalt aggregate), manufacturing of stone wool insulation, and as a decorative landscaping stone.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found on the Moon, Mars, and Venus.
Field identification & locations
Identify by its dark color, heavy weight for its size, and absence of large visible crystals. Commonly found in volcanic regions and ocean beaches.
