igneous
Red Scoria
Scoria (Vesicular Basaltic Andesite)
Hardness: 5-6 (Mohs); Color: Reddish-brown to dark red; Luster: Dull/Earthy; Structure: Vesicular (highly porous/pitted); Specific Gravity: 0.8-2.1 (lightweight)
- Hardness
- 5-6 (Mohs)
- Color
- Reddish-brown to dark red
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-6 (Mohs); Color: Reddish-brown to dark red; Luster: Dull/Earthy; Structure: Vesicular (highly porous/pitted); Specific Gravity: 0.8-2.1 (lightweight)
Formation & geological history
Formed during explosive volcanic eruptions where trapped gas bubbles (vesicles) are frozen into cooling lava. The red color is caused by the oxidation of iron (rusting) within the lava during or after eruption.
Uses & applications
Used extensively in landscaping, gas grill briquettes, high-temperature insulation, drainage systems, and as a lightweight aggregate in concrete.
Geological facts
Scoria is often confused with pumice; however, scoria has larger vesicles and thicker cell walls, making it dense enough to usually sink in water, whereas pumice often floats.
Field identification & locations
Identify by its characteristic 'cinder' look, many small holes, and lightweight feel. Commonly found in volcanic fields, cinder cones, and near basaltic lava flows.
