igneous
Scoria
Extrusive Igneous Rock
Hardness: 5-6 on the Mohs scale. Color: Dark brown, reddish-brown, or black. Luster: Dull. Crystal structure: Aphanitic (fine-grained) with abundant vesicular texture (gas bubbles). Specific gravity: Variable, but often low enough to float briefly if trapped air is present.
- Hardness
- 5-6 on the Mohs scale
- Color
- Dark brown, reddish-brown, or black
- Luster
- Dull
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Physical properties
Hardness: 5-6 on the Mohs scale. Color: Dark brown, reddish-brown, or black. Luster: Dull. Crystal structure: Aphanitic (fine-grained) with abundant vesicular texture (gas bubbles). Specific gravity: Variable, but often low enough to float briefly if trapped air is present.
Formation & geological history
Formed through explosive volcanic eruptions when gas-rich mafic or intermediate magma is ejected into the atmosphere, cooling rapidly while gases escape, leaving behind a vesicular, frothy texture. Geological age varies widely depending on the volcanic deposit.
Uses & applications
Used in landscaping, lightweight aggregate in concrete, gas barbecue grills, water filtration, and as an abrasive in personal care products.
Geological facts
Scoria is similar to pumice, but it is darker, has a higher specific gravity, and features larger, less uniform vesicles with thicker walls. Unlike pumice, most scoria will sink in water.
Field identification & locations
Easily identified by its dark color, rough texture, and numerous air pockets (vesicles). Commonly found around volcanic cinder cones worldwide.
