igneous
Vesicular Basalt (Lava Rock)
Scoriaceous Basalt
Hardness: 5-6 Mohs; Color: Dark grey to black; Luster: Dull to earthy; Structure: Aphanitic with vesicles (gas bubbles); Specific Gravity: 2.8–3.0
- Hardness
- 5-6 Mohs
- Color
- Dark grey to black
- Luster
- Dull to earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 Mohs; Color: Dark grey to black; Luster: Dull to earthy; Structure: 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 at the Earth's surface. The holes (vesicles) are created by trapped gas bubbles escaping during solidification.
Uses & applications
Used in landscaping, gas grills (lava rocks), road construction aggregate, and as a lightweight abrasive in stone-washing textiles.
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 extensively on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (relative to pumice), and distinctive 'Swiss cheese' porous texture. Common in volcanic regions like Hawaii, Iceland, and the Pacific Northwest.
