igneous
Vesicular Basalt (Lava Rock)
Vesicular Basalt
Hardness: 5-6 Mohs. Color: dark gray to black. Luster: dull to earthy. Texture: vesicular (pitted with gas bubbles). Specific gravity: 2.8-3.0.
- Hardness
- 5-6 Mohs
- Color
- dark gray to black
- Luster
- dull to earthy
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Physical properties
Hardness: 5-6 Mohs. Color: dark gray to black. Luster: dull to earthy. Texture: vesicular (pitted with gas bubbles). Specific gravity: 2.8-3.0.
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava (basaltic) erupted from a volcano. The holes (vesicles) are created by trapped gas bubbles escaping as the rock solidifies.
Uses & applications
Used in landscaping, BBQ grills as heat retainers, road construction aggregate, and lightweight concrete production.
Geological facts
Basalt is the most common rock type in the Earth's crust and makes up most of the ocean floor. When the vesicles are later filled with minerals like zeolite or quartz, it is called amygdaloidal basalt.
Field identification & locations
Identify by its dark color, heavy weight compared to pumice, and characteristic holes. Commonly found in volcanic fields, Hawaii, and the Pacific Northwest.
