igneous
Basaltic Scoria
Scoria (vesicular basalt)
Hardness: 5-6 (Mohs scale); Color: Dark gray, black, or reddish-brown; Luster: Dull/earthy; Crystal Structure: Aphanitic (fine-grained) with high vesicularity; Specific Gravity: 2.5-3.0 (though it often floats temporarily due to air pockets).
- Hardness
- 5-6 (Mohs scale)
- Color
- Dark gray, black, or reddish-brown
- Luster
- Dull/earthy
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Dark gray, black, or reddish-brown; Luster: Dull/earthy; Crystal Structure: Aphanitic (fine-grained) with high vesicularity; Specific Gravity: 2.5-3.0 (though it often floats temporarily due to air pockets).
Formation & geological history
Formed from the rapid cooling of gas-rich basaltic lava ejected from a volcano. As the lava cools, trapped gas bubbles form the characteristic holes (vesicles). Found in volcanic fields globally.
Uses & applications
Used extensively in landscaping, gas grill lava rocks, drainage systems, lightweight concrete aggregates, and road construction.
Geological facts
Scoria is often confused with pumice; however, scoria is denser, has larger vesicles, and is typically darker in color due to a higher iron and magnesium content.
Field identification & locations
Identify by its 'sponge-like' appearance, dark color, and rough, jagged edges. Common near cinder cones and basaltic lava flows in places like Iceland, Hawaii, and Arizona.
