igneous
Basalt
Basalt
Hardness: 6 on Mohs scale; Color: Dark grey to black, weathering to brown or green; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic (fine-grained); Cleavage: Non-existent; Specific gravity: 2.8–3.0
- Hardness
- 6 on Mohs scale
- Color
- Dark grey to black, weathering to brown or green
- Luster
- Dull to sub-vitreous
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6 on Mohs scale; Color: Dark grey to black, weathering to brown or green; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic (fine-grained); Cleavage: Non-existent; 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. It is the most common volcanic rock on Earth.
Uses & applications
Extensively used in construction for aggregate, road base, railroad ballast, and high-quality concrete. Also used for stone carving and as a raw material for cast basalt liners.
Geological facts
Basalt underlies more of Earth's surface than any other rock type; most ocean basins are underlain by basalt. It is also found on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (density), and lack of visible crystals. It typically has a fine-grained texture. Commonly found in lava flows and volcanic provinces.
