igneous
Vesicular Basalt (Scoria)
Vesicular Basalt
Hardness: 5-6 Mohs. Color: Reddish-brown to black. Luster: Dull/Earthy. Structure: Microcrystalline with numerous vesicles (holes). Cleavage: None. Specific Gravity: 2.5-3.0.
- Hardness
- 5-6 Mohs
- Color
- Reddish-brown to black
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-6 Mohs. Color: Reddish-brown to black. Luster: Dull/Earthy. Structure: Microcrystalline with numerous vesicles (holes). Cleavage: None. Specific Gravity: 2.5-3.0.
Formation & geological history
Formed through the rapid cooling of lava rich in dissolved gases. As the lava depressurizes at the surface, gas bubbles expand and become trapped as the rock solidifies.
Uses & applications
Used frequently in landscaping, gas grills (lava rocks), drainage systems, and as an abrasive in concrete or stonewashed denim production.
Geological facts
The holes, or vesicles, are frozen records of gas bubbles from a volcanic eruption. If the vesicles are extremely dense, the rock may even float briefly in water.
Field identification & locations
Identify by its 'Swiss cheese' appearance and lightweight feel compared to solid rock. Commonly found in volcanic fields, especially near cinder cones and basaltic flows.
