igneous
Basalt (Vesicular)
Extrusive Igneous Rock
Hardness: 5-6 on the Mohs scale; Color: Dark grey to black; Luster: Dull; Structure: Aphanitic with vesicles (holes formed by trapped gas bubbles); Specific gravity: 2.8-3.0
- Hardness
- 5-6 on the Mohs scale
- Color
- Dark grey to black
- Luster
- Dull
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Physical properties
Hardness: 5-6 on the Mohs scale; Color: Dark grey to black; Luster: Dull; Structure: Aphanitic with vesicles (holes formed by trapped gas bubbles); Specific gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of low-viscosity, gas-rich basaltic lava erupted on or near the Earth's surface. Geologically young to ancient.
Uses & applications
Used in construction, road aggregate, landscaping, barbecues, and lightweight aggregate.
Geological facts
Vesicular basalt forms when gas bubbles are trapped in the cooling lava. When it cools extremely rapidly with high gas content, it forms scoria or pumice, but vesicular basalt retains a denser rock matrix.
Field identification & locations
Easily identified by its dark color, heavy feel relative to its size, and numerous vesicular cavities. Found abundantly worldwide in volcanic regions, oceanic crust, and basalt flood provinces.
