igneous
Basalt (Vesicular)
Basalt
Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Structure: Fine-grained (aphanitic) with vesicles; Specific Gravity: 2.8 to 3.0
- Hardness
- 6
- Color
- Dark grey to black
- Luster
- Dull to sub-metallic
Identified More igneous →
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Physical properties
Hardness: 6.0; Color: Dark grey to black; Luster: Dull to sub-metallic; Structure: Fine-grained (aphanitic) with vesicles; Specific Gravity: 2.8 to 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or very near the Earth's surface. The holes (vesicles) are created by trapped gas bubbles during solidification.
Uses & applications
Used in road construction as aggregate, in concrete, as asphalt filler, and for stone wool insulation. Also popular in aquarium landscaping and BBQ grill rock.
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 on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (relative to size), and the presence of small circular pits. Commonly found in volcanic regions like Hawaii, Iceland, and the Pacific Northwest.
