igneous
Scoria
Vesicular Basalt / Scoria
Hardness: 5-6 (Mohs); Color: dark brown, black, or reddish-brown; Luster: dull to submetallic; Structure: vesicular (pitted with gas bubbles); Specific Gravity: 0.8-2.1 (low, but usually sinks in water).
- Hardness
- 5-6 (Mohs)
- Color
- dark brown, black, or reddish-brown
- Luster
- dull to submetallic
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Physical properties
Hardness: 5-6 (Mohs); Color: dark brown, black, or reddish-brown; Luster: dull to submetallic; Structure: vesicular (pitted with gas bubbles); Specific Gravity: 0.8-2.1 (low, but usually sinks in water).
Formation & geological history
Formed from gas-rich basaltic magma during explosive volcanic eruptions. As the lava cools rapidly, trapped gas bubbles form the characteristic holes (vesicles). Found in volcanic regions worldwide.
Uses & applications
Used in landscaping for ground cover, as a drainage material, in lightweight concrete blocks, and as high-temperature insulation in outdoor gas grills and fire pits.
Geological facts
Scoria is often mistaken for pumice; however, scoria has thicker vesicle walls and is denser, meaning it usually sinks in water while pumice floats. It is a major component of cinder cones.
Field identification & locations
Identify by its light weight relative to appearance and the presence of numerous open pores. Commonly found near volcanic mountains and lava fields like those in Iceland, Hawaii, or Italy.
