igneous
Vesicular Basalt
Vesicular Basalt
Hardness: 5-6 Mohs. Color: dark gray to black, often weathering to brownish tones. Luster: dull to earthy. Crystal structure: fine-grained (aphanitic) with visible vesicles (gas bubbles).
- Hardness
- 5-6 Mohs
- Color
- dark gray to black, often weathering to brownish tones
- Luster
- dull to earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 Mohs. Color: dark gray to black, often weathering to brownish tones. Luster: dull to earthy. Crystal structure: fine-grained (aphanitic) with visible vesicles (gas bubbles).
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 that were trapped in the lava as it solidified.
Uses & applications
Used in construction as road base, concrete aggregate, and railroad ballast. Highly vesicular varieties like scoria are used in landscaping and 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, fine-grained texture, and characteristic 'pitting' from gas bubbles. Often found in volcanic regions or as river-worn cobbles in drainages from volcanic highlands.
