igneous
Vesicular Basalt
Vesicular Basalt
Hardness: 5-6 (Mohs); Color: Dark gray to black; Luster: Dull or earthy; Structure: Aphanitic (fine-grained) with vesicles; Cleavage: None; Specific Gravity: 2.8 - 3.0
- Hardness
- 5-6 (Mohs)
- Color
- Dark gray to black
- Luster
- Dull or earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 (Mohs); Color: Dark gray to black; Luster: Dull or earthy; Structure: Aphanitic (fine-grained) with vesicles; Cleavage: None; Specific Gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava (basaltic magma) at or near the Earth's surface. The holes (vesicles) are created by gas bubbles trapped in the cooling lava. Common in volcanic active zones.
Uses & applications
Used in construction as road base, railroad ballast, and ground cover in landscaping. Highly porous varieties (scoria) are used as gas grill rocks and in lightweight concrete.
Geological facts
Basalt is the most common rock type on the Earth's crust and makes up most of the ocean floor. It is also found extensively on the Moon and Mars.
Field identification & locations
Identify by its dark color, heavy weight (relative to size, unless highly vesicular), and the presence of small pits or holes on the surface. Commonly found in volcanic regions like Hawaii, Iceland, and the Pacific Northwest.
