igneous
Basalt
Mafic Igneous Rock
Hardness: 6-7 (Mohs scale), Color: Dark grey to black, Luster: Dull/Sub-metallic, Structure: Fine-grained (aphanitic), Specific Gravity: 2.8-3.0
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Dark grey to black, Luster: Dull/Sub-metallic, 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
Extensively used in construction for aggregate, road base, railroad ballast, and high-quality concrete. Can also be used for flooring and industrial sculpture.
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 common on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (relative to size), and fine-grained texture which lacks visible crystals to the naked eye. Found worldwide in volcanic regions.
