igneous
Scoria (Lava Rock)
Mafic Vesicular Volcanic Rock
Hardness: 5-6 (Mohs scale); Color: Dark red, black, or dark brown; Luster: Dull to sub-vitreous; Structure: Vesicular (highly porous/holed); Specific Gravity: 0.8-2.1 (relatively light)
- Hardness
- 5-6 (Mohs scale)
- Color
- Dark red, black, or dark brown
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Dark red, black, or dark brown; Luster: Dull to sub-vitreous; Structure: Vesicular (highly porous/holed); Specific Gravity: 0.8-2.1 (relatively light)
Formation & geological history
Formed from gas-rich mafic magma cooling rapidly during a volcanic eruption. Gases expand and form bubbles (vesicles) while the lava solidifies. It is primarily found in recent volcanic landscapes (Cenozoic era).
Uses & applications
Used widely in landscape gardening, gas grills, high-temperature insulation, drainage systems, and as an abrasive in stone-washing denim.
Geological facts
Scoria is different from Pumice; whereas Pumice is light enough to float on water, Scoria is more dense and usually sinks. It is the primary component of many cinder cones (volcanic peaks).
Field identification & locations
Identify in the field by its sponge-like appearance, sharp edges, and dark color. It is extremely common in volcanic regions like Iceland, Hawaii, and Italy. Collectors value it for terrariums and aquariums.
