igneous
Basalt Scoria
Aphanitic basaltic scoria
Hardness: 5-6 Mohs; Color: Dark grey to black with reddish-brown oxidation; Luster: Dull/earthy; Crystal structure: Microcrystalline/glassy; Vesicular (bubbly) texture.
- Hardness
- 5-6 Mohs
- Color
- Dark grey to black with reddish-brown oxidation
- Luster
- Dull/earthy
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Physical properties
Hardness: 5-6 Mohs; Color: Dark grey to black with reddish-brown oxidation; Luster: Dull/earthy; Crystal structure: Microcrystalline/glassy; Vesicular (bubbly) texture.
Formation & geological history
Formed from the rapid cooling of gas-rich basaltic lava during explosive volcanic eruptions. The holes (vesicles) are formed by trapped gas bubbles.
Uses & applications
Landscaping, drainage, lightweight aggregate in concrete, road base, and as a natural abrasive or 'lava rock' for gas grills.
Geological facts
Scoria is often mistaken for pumice; however, scoria sinks in water because it has thicker cell walls and a higher density than pumice.
Field identification & locations
Identified by its highly porous, jagged surface and dark color. Common in volcanic fields such as those in Iceland, Hawaii, and the Western United States.
