igneous
Scoria
Scoria (vesicular volcanic rock)
Hardness: 5-6 Mohs; Color: Dark brown, black, or reddish-brown; Luster: Dull (sub-vitreous); Crystal Structure: Aphanitic with high vesicularity; Specific Gravity: Low (often floats briefly/sinks slowly)
- Hardness
- 5-6 Mohs
- Color
- Dark brown, black, or reddish-brown
- Luster
- Dull (sub-vitreous)
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Physical properties
Hardness: 5-6 Mohs; Color: Dark brown, black, or reddish-brown; Luster: Dull (sub-vitreous); Crystal Structure: Aphanitic with high vesicularity; Specific Gravity: Low (often floats briefly/sinks slowly)
Formation & geological history
Formed during explosive volcanic eruptions where magma containing high concentrations of gas is ejected into the air, cooling quickly and trapping gas bubbles as vesicles.
Uses & applications
Used extensively in landscaping, gas grill lava rocks, high-temperature insulation, and as a lightweight aggregate in concrete or drainage systems.
Geological facts
Scoria differs from pumice because it has larger vesicles and thicker cell walls, making it denser. If it has enough trapped air, it can sometimes be mistake for pumice.
Field identification & locations
Identify by its rough, vesicular (holed) surface and dark color. Common in volcanic regions like Iceland, Hawaii, and Italy. Often found near cinder cones.
