igneous
Red Scoria (Lava Rock)
Scoria (Extrusive Igneous Rock / Mafic composition)
Vesicular texture (pitted with holes); Hardness: 5-6 (Mohs); Color: Reddish-brown to dark red; Luster: Dull/Earthy; Crystal structure: Glassy/Aphanitic; Specific gravity: 0.8-2.6 (though often floats briefly in water due to trapped air).
- Hardness
- 5-6 (Mohs)
- Color
- Reddish-brown to dark red
- Luster
- Dull/Earthy
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Physical properties
Vesicular texture (pitted with holes); Hardness: 5-6 (Mohs); Color: Reddish-brown to dark red; Luster: Dull/Earthy; Crystal structure: Glassy/Aphanitic; Specific gravity: 0.8-2.6 (though often floats briefly in water due to trapped air).
Formation & geological history
Formed from gas-rich basaltic or andesitic magma. As the lava is ejected during a volcanic eruption, it cools rapidly while gas bubbles are still trapped inside, creating the vesicular holes. Commonly found in cinder cones and volcanic fields produced during the Holocene to Pleistocene epochs.
Uses & applications
Used extensively in landscaping, gas grill briquettes, drainage stone, high-temperature insulation, and lightweight concrete aggregates. In some cases, it is used for foot pumice or abrasive cleaning.
Geological facts
Red scoria gets its color from the oxidation of iron within the lava while it is still hot. It is the primary component of many cinder cone volcanoes, such as those found in the American Southwest or Iceland.
Field identification & locations
Identify in the field by its very lightweight, 'sponge-like' appearance and sharp, jagged edges. It is often found in volcanic regions like Arizona, Hawaii, and Italy. Collectors look for pieces with unique cooling patterns or embedded crystals like olivine.
