igneous
Basalt
Basalt
Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained) to porphyritic; Cleavage: None/Irregular; Specific Gravity: 2.8 - 3.0.
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull to sub-metallic
Identified More igneous →
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Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Crystal structure: Aphanitic (fine-grained) to porphyritic; Cleavage: None/Irregular; 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 Earth's surface. It can be found in volcanic regions, oceanic crust, and plateaus.
Uses & applications
Used extensively in construction as aggregate for roads and concrete, in floor tiles, and in statues. Fibers are also used in high-performance insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It also exists on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (relative to size), and fine grain. Crystals (phenocrysts) are often too small to see with the naked eye without a loupe. Found globally in volcanic areas.
