igneous
Basalt
Basalt (Ma-Fe Silicate)
Hardness: 6 (Mohs scale); Color: Dark gray to black; Luster: Dull or earthy; Crystal structure: Aphanitic (fine-grained); Cleavage: None; Specific gravity: 2.8 - 3.0
- Hardness
- 6 (Mohs scale)
- Color
- Dark gray to black
- Luster
- Dull or earthy
Identified More igneous →
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Physical properties
Hardness: 6 (Mohs scale); Color: Dark gray to black; Luster: Dull or earthy; Crystal structure: Aphanitic (fine-grained); Cleavage: None; Specific gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the Earth's surface. Found in oceanic crust and volcanic regions.
Uses & applications
Used primarily in construction for road base, concrete aggregate, ballast, and occasionally for high-durability floor tiles.
Geological facts
Basalt is the most common rock in the Earth's crust and covers most of the ocean floor. It is also common on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight for its size, and absence of visible large crystals. Commonly found in volcanic fields or as river cobbles in volcanic drainage areas.
