igneous
Basalt
Basalt
Hardness: 6 on Mohs scale; Color: Dark grey to black; Luster: Dull/Matte; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8–3.0
- Hardness
- 6 on Mohs scale
- Color
- Dark grey to black
- Luster
- Dull/Matte
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Physical properties
Hardness: 6 on Mohs scale; Color: Dark grey to black; 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.
Uses & applications
Widely used in construction for aggregate, road base, railroad ballast, and high-quality concrete. It can also be used in floor tiles and monuments.
Geological facts
Basalt is the most common rock type in the Earth's crust, making up most of the ocean floor. It is also found on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (density), and fine-grained texture. Commonly found in volcanic regions, oceanic islands, and mid-ocean ridges.
