igneous
Scoria
Vesicular Basalt / Scoria
Hardness 5-6 (Mohs); Color: dark red, brown, or black; Luster: earthy/dull; Texture: vesicular (highly porous); Specific Gravity: 0.8 - 2.1 (relatively light weighting).
- Color
- dark red, brown, or black
- Luster
- earthy/dull
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Physical properties
Hardness 5-6 (Mohs); Color: dark red, brown, or black; Luster: earthy/dull; Texture: vesicular (highly porous); Specific Gravity: 0.8 - 2.1 (relatively light weighting).
Formation & geological history
Formed from gas-rich basaltic or andesitic magma expelled during volcanic eruptions. As the lava cools rapidly, trapped gas bubbles leave behind holes or vesicles. Most specimens are relatively young, from the Cenozoic era.
Uses & applications
Used widely in landscaping (lava rock), as a lightweight aggregate in concrete, for high-temperature insulation, and in traction control on icy roads.
Geological facts
Scoria is different from pumice because it has larger vesicles and thicker cell walls, and unlike pumice, it usually sinks in water. It is a major component of volcanic cinder cones.
Field identification & locations
Identify by its 'bubbly' or honeycomb appearance and reddish-brown color. Found in volcanic regions like Iceland, Hawaii, the Canary Islands, and the Western United States.
