igneous
Vesicular Basalt
Basalt (Extrusive Igneous Rock)
Hardness: 5-6 Mohs; Color: Dark grey to black or dark greenish-black; Luster: Dull to sub-metallic; Structure: Fine-grained/aphanitic with vesicles (gas bubbles); Specific Gravity: 2.8-3.0.
- Hardness
- 5-6 Mohs
- Color
- Dark grey to black or dark greenish-black
- Luster
- Dull to sub-metallic
Identified More igneous →
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Physical properties
Hardness: 5-6 Mohs; Color: Dark grey to black or dark greenish-black; Luster: Dull to sub-metallic; Structure: Fine-grained/aphanitic with vesicles (gas bubbles); 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 moon. The 'holes' are vesicles formed by trapped gas during eruption.
Uses & applications
Used in construction for road base, concrete aggregate, and railroad ballast. Decorative uses in landscaping and aquariums.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. It is also found in abundance on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (relative to size), and distinct pitting or holes. Commonly found in volcanic regions and coastal areas where it has been tumbled by waves.
