igneous
Scoria
Vesicular Basalt / Scoria
Hardness: 5-6 (Mohs). Color: Black, dark gray, reddish-brown. Luster: Dull/Glassy. Structure: Vesicular (bubble-like holes). Specific Gravity: 2.5-3.0 (though it feels light due to air pockets).
- Hardness
- 5-6 (Mohs)
- Color
- Black, dark gray, reddish-brown
- Luster
- Dull/Glassy
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Physical properties
Hardness: 5-6 (Mohs). Color: Black, dark gray, reddish-brown. Luster: Dull/Glassy. Structure: Vesicular (bubble-like holes). Specific Gravity: 2.5-3.0 (though it feels light due to air pockets).
Formation & geological history
Formed from gas-rich mafic magma (basaltic) that is ejected from a volcano. As the lava solidifies rapidly, gas bubbles are trapped, creating a porous texture. Typically found in cinder cones.
Uses & applications
Used extensively in landscaping, gas grill lava rocks, high-temperature insulation, drainage stones, and as a lightweight aggregate in concrete blocks.
Geological facts
Scoria is different from Pumice; Scoria has larger vesicles, thicker walls, and is denser, meaning it usually sinks in water while pumice floats.
Field identification & locations
Identify by its dark color (black or red), rough sandpaper-like texture, and many small visible holes (vesicles). Commonly found near volcanic sites like Craters of the Moon or Hawaiian volcanic fields.
