igneous
Basalt
Basalt
Hardness: 6.0; Color: Dark grey to black, sometimes greenish; Luster: Dull/Matte; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8 - 3.0.
- Hardness
- 6
- Color
- Dark grey to black, sometimes greenish
- Luster
- Dull/Matte
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Physical properties
Hardness: 6.0; Color: Dark grey to black, sometimes greenish; Luster: Dull/Matte; Crystal structure: Aphanitic (fine-grained); 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. It is the most common volcanic rock on Earth.
Uses & applications
Extensively used in construction for aggregate, road base, railroad ballast, and high-quality concrete. It is also used as dimension stone and for industrial floor tiles.
Geological facts
Basalt underlies more of Earth's surface than any other rock type. It is the chief component of the oceanic crust and is also found on the Moon, Mars, and Venus.
Field identification & locations
Identify by its weight (dense), dark color, and fine-grained texture which lacks visible crystals to the naked eye. Commonly found at volcanic sites, ocean ridges, and large plateau regions like the Deccan Traps.
