igneous
Basalt Pebble
Extrusive Igneous Rock
Hardness: 6 on Mohs scale; Color: Dark grey to black; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic, fine-grained; Specific gravity: 2.8-3.0
- Hardness
- 6 on Mohs scale
- Color
- Dark grey to black
- Luster
- Dull to sub-vitreous
Identified More igneous →
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Physical properties
Hardness: 6 on Mohs scale; Color: Dark grey to black; Luster: Dull to sub-vitreous; Crystal structure: Aphanitic, fine-grained; Specific gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity basaltic lava exposed at or very near the Earth's surface, often shaped and smoothed by water transport in rivers or beaches.
Uses & applications
Used in construction, aggregate, road building, railroad ballast, and sometimes for landscaping or massage stones.
Geological facts
Basalt is the most common rock type in the Earth's crust underlying the world's ocean basins, and it is also commonly found on the Moon and Mars.
Field identification & locations
Found abundantly in riverbeds, beaches, and volcanic regions worldwide; easily identified by its dark color, fine-grained texture, and high density.
