igneous
Red Scoria
Scoria (Basaltic Scoria)
Hardness: 5.0-6.0; Color: Reddish-brown to dark red; Luster: Dull/Earthy; Structure: Highly vesicular (porous); Cleavage: None; Specific Gravity: Low (often floats in water initially but sinks)
- Hardness
- 5
- Color
- Reddish-brown to dark red
- Luster
- Dull/Earthy
Identified More igneous →
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Physical properties
Hardness: 5.0-6.0; Color: Reddish-brown to dark red; Luster: Dull/Earthy; Structure: Highly vesicular (porous); Cleavage: None; Specific Gravity: Low (often floats in water initially but sinks)
Formation & geological history
Formed from gas-rich basaltic or andesitic magma. During a volcanic eruption, gases dissolve out of the melt as it reaches the surface, creating holes (vesicles) as the lava solidifies quickly. Common in cinder cones.
Uses & applications
Used extensively in landscaping, gas grill lava rocks, high-temperature insulation, lightweight concrete aggregate, and road traction in snowy conditions.
Geological facts
Scoria is often confused with pumice, but it is denser and has larger vesicles with thicker cell walls. The red color is caused by the oxidation of iron within the lava during or after the eruption.
Field identification & locations
Identify by its 'Swiss cheese' texture and light weight relative to solid basalt. Commonly found near active or dormant volcanic regions like the American West (Arizona, New Mexico), Iceland, and Italy.
