igneous
Scoria
Vesicular Basalt / Scoria
Hardness: 5-6 Mohs. Color: Reddish-brown to dark black. Luster: Dull/Earthy. Structure: Highly vesicular (pitted with gas bubbles). Specific Gravity: 2.5-3.0 (often feels surprisingly light).
- Hardness
- 5-6 Mohs
- Color
- Reddish-brown to dark black
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-6 Mohs. Color: Reddish-brown to dark black. Luster: Dull/Earthy. Structure: Highly vesicular (pitted with gas bubbles). Specific Gravity: 2.5-3.0 (often feels surprisingly light).
Formation & geological history
Formed from gas-rich basaltic magma cooling rapidly during volcanic eruptions. The vesicles are formed by trapped gas bubbles. Typically Cenozoic in age.
Uses & applications
Used in landscaping (lava rocks), high-heat insulation, concrete aggregate, and as an abrasive in stone-washing textiles.
Geological facts
Scoria is different from pumice because it has thicker cell walls and can sink in water, whereas pumice often floats. It is a main component of cinder cones.
Field identification & locations
Identify by its 'Swiss cheese' appearance and rough, abrasive texture. Commonly found in volcanic fields, near vents, and cinder cones in regions like the American West or Iceland.
