igneous
Red Scoria
Scoria (Vesicular Basalt/Andesite)
Hardness: 5-6 (Mohs scale), Color: Reddish-brown to dark red, Luster: Dull/Earthy, Crystal Structure: Aphanitic (fine-grained) with high vesicularity (pocked marks/holes), Specific Gravity: Low (often floats briefly/feels light)
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Physical properties
Hardness: 5-6 (Mohs scale), Color: Reddish-brown to dark red, Luster: Dull/Earthy, Crystal Structure: Aphanitic (fine-grained) with high vesicularity (pocked marks/holes), Specific Gravity: Low (often floats briefly/feels light)
Formation & geological history
Formed from gas-rich basaltic or andesitic magma erupting from a volcano. As the lava cools rapidly, trapped gas bubbles form the characteristic vesicles. Red color comes from oxidation of iron within the lava during or after eruption.
Uses & applications
Extensively used in landscaping, gas grill lava rocks, high-temperature insulation, drainage systems, and as a lightweight aggregate in concrete.
Geological facts
Scoria is different from pumice because it has larger vesicles and thicker cell walls, making it denser. The red color is a result of high iron content rusting into hematite.
Field identification & locations
Identify by its 'sponge-like' appearance and light weight. Commonly found near cinder cones and volcanic rift zones such as those in Iceland, Italy, and the Western United States.
