igneous
Scoria (Lava Rock)
Scoria (Vesicular Basaltic Glass/Rock)
Hardness: 5-6 Mohs. Color: Reddish-brown to dark brown/black. Luster: Dull/Earthy. Structure: Highly vesicular (honeycombed with gas bubbles). Cleavage: None. Specific Gravity: Typically low due to air pockets, sometimes floats on water temporarily.
- Hardness
- 5-6 Mohs
- Color
- Reddish-brown to dark brown/black
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-6 Mohs. Color: Reddish-brown to dark brown/black. Luster: Dull/Earthy. Structure: Highly vesicular (honeycombed with gas bubbles). Cleavage: None. Specific Gravity: Typically low due to air pockets, sometimes floats on water temporarily.
Formation & geological history
Formed from gas-rich basaltic magma cooling rapidly during a volcanic eruption (extrusive igneous). The gas bubbles are trapped as the lava solidifies, creating the porous texture. Common in Cenozoic volcanic fields.
Uses & applications
Used widely in landscaping (lava rock), as high-temperature insulation, in gas grills to distribute heat, and sometimes as a lightweight aggregate for concrete or as a drainage material.
Geological facts
Scoria is often confused with pumice; however, scoria has thicker vesicle walls and is denser, usually sinking in water, whereas pumice often floats. The red color is typically due to the oxidation of iron within the lava.
Field identification & locations
Identify in the field by its very high porosity, rough abrasive texture, and dark red or black color. Found near cinder cones and volcanic craters globally, such as in the Western US, Iceland, and Italy.
