igneous
Basalt (Vesicular)
Vesicular Basalt
Hardness: 5-6 (Mohs); Color: Dark grey to greenish-black with brownish weathering; Luster: Dull/Earthy; Structure: Fine-grained (aphanitic) with small pits or holes (vesicles); Specific Gravity: 2.8-3.0.
- Hardness
- 5-6 (Mohs)
- Color
- Dark grey to greenish-black with brownish weathering
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-6 (Mohs); Color: Dark grey to greenish-black with brownish weathering; Luster: Dull/Earthy; Structure: Fine-grained (aphanitic) with small pits or holes (vesicles); Specific Gravity: 2.8-3.0.
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 gas bubbles trapped in the cooling lava. Most found on surface are Cenozoic in age.
Uses & applications
Commonly used in construction as aggregate for roads and concrete. In landscaping, it is used for decorative stones. High-quality pieces are used for stone massage or aquarium decor.
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
Look for a heavy, dark-colored rock with a fine-grained texture and small gas-bubble pits. Often found in volcanic regions or riverbeds where volcanic rocks have been transported upstream.
