igneous
Vesicular Basalt
Extrusive mafic igneous rock
Hardness: 6-7 (Mohs); Color: Dark grey to black; Luster: Dull to sub-vitreous; Structure: Vesicular (contains air bubbles/pores); Specific Gravity: 2.8-3.0
- Hardness
- 6-7 (Mohs)
- Color
- Dark grey to black
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 6-7 (Mohs); Color: Dark grey to black; Luster: Dull to sub-vitreous; Structure: Vesicular (contains air bubbles/pores); 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 caused by escaping gas during solidification.
Uses & applications
Used in construction as road aggregate, railroad ballast, and for decorative landscaping. Some vesicular basalt is used as 'scoria' or 'lava rock' for gas grills.
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 characteristic holes or pits. Commonly found in volcanic regions such as Hawaii, Iceland, and the Pacific Northwest.
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