igneous
Basalt
Basalt (Aphanitic Mafic Igneous Rock)
Hardness: 6 on Mohs scale; Color: dark grey to black; Luster: dull to sub-metallic; Crystal structure: fine-grained (aphanitic) or glassy; Specific gravity: 2.8–3.0
- Hardness
- 6 on Mohs scale
- Color
- dark grey to black
- Luster
- dull to sub-metallic
Identified More igneous →
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Physical properties
Hardness: 6 on Mohs scale; Color: dark grey to black; Luster: dull to sub-metallic; Crystal structure: fine-grained (aphanitic) or glassy; 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
Extensively used in construction for aggregate, road base, railroad ballast, and high-quality concrete. Also used for stone carvings and floor tiles.
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, Mars, and Venus.
Field identification & locations
Identify by its dark color, heavy weight for its size (density), and lack of visible crystals to the naked eye. Commonly found in volcanic regions and oceanic crustal outcrops.
