igneous
Vesicular Basalt (Pumice-like)
Vesicular Basalt
Hardness: 5-6 (Mohs); Color: Gray to dark charcoal; Luster: Dull/Earthy; Structure: Aphanitic with vesicles (gas bubbles); Specific Gravity: 2.8-3.0
- Hardness
- 5-6 (Mohs)
- Color
- Gray to dark charcoal
- Luster
- Dull/Earthy
Identified More igneous →
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Physical properties
Hardness: 5-6 (Mohs); Color: Gray to dark charcoal; Luster: Dull/Earthy; Structure: Aphanitic with vesicles (gas bubbles); Specific Gravity: 2.8-3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava. Bubbles of gas (vesicles) are trapped as the lava solidifies near the surface of a volcano.
Uses & applications
Used in landscaping, as a decorative stone, in gas grills for heat retention, and as an abrasive in industrial scrubbing or skincare (pumice style).
Geological facts
This specimen appears to be a water-worn or weathered 'river rock' version of vesicular basalt, giving it a characteristic egg shape. Basalt is the most common rock type on Earth\'s crust and also makes up much of the surface of the Moon and Mars.
Field identification & locations
Identify by its lightweight feel relative to size, pitted (vesicular) surface, and dark gray color. Commonly found in volcanic regions, near ancient lava flows, or as pebbles in riverbeds downstream from volcanic sources.
