igneous
Basalt
Basalt
Hardness: 6 on Mohs scale; Color: Dark grey to black; Luster: Dull; Crystal structure: Aphanitic (fine-grained); Specific gravity: 2.8–3.0
- Hardness
- 6 on Mohs scale
- Color
- Dark grey to black
- Luster
- Dull
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Physical properties
Hardness: 6 on Mohs scale; Color: Dark grey to black; Luster: Dull; 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
Used primarily as crushed stone for road base, concrete aggregate, and railroad ballast. Also used as decorative masonry or in high-temperature insulation materials.
Geological facts
Basalt is the most common rock type in the Earth's crust and covers most of the ocean floor. It is also found on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight for its size, and absence of large visible crystals. Commonly found in coastal areas or volcanic regions.
