igneous
Vesicular Basalt
Mafic Volcanic Rock (Basalt)
Hardness: 6 (Mohs); Color: Dark gray to black; Luster: Dull or earthy; Structure: Vesicular (pitted with gas bubbles); Specific Gravity: 2.8-3.0; Aphanitic texture.
- Hardness
- 6 (Mohs)
- Color
- Dark gray to black
- Luster
- Dull or earthy
Identified More igneous →
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Physical properties
Hardness: 6 (Mohs); Color: Dark gray to black; Luster: Dull or earthy; Structure: Vesicular (pitted with gas bubbles); Specific Gravity: 2.8-3.0; Aphanitic texture.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at the Earth's surface. The pits (vesicles) are created by gas bubbles that were trapped as the lava solidified. Primarily found in oceanic crust and volcanic hotspots.
Uses & applications
Commonly used in landscaping as decorative stone, construction aggregate, railroad ballast, and ground into stone wool for insulation.
Geological facts
Basalt is the most common rock type in the Earth's crust and also covers large areas of the Moon, Mars, and Venus. The holes in vesicular basalt can often become filled with secondary minerals like quartz or calcite to form amygdaloids.
Field identification & locations
Identify by its dark color, heavy weight (relative to size), and characteristic swiss-cheese-like holes. Found globally in volcanic regions like Hawaii, Iceland, and the Pacific Northwest.
