igneous
Weathered vesicular volcanic rock, likely scoria
Scoria; composition commonly basaltic to andesitic
AI-generated identification · may be incorrectDark gray-brown, highly vesicular, dull to slightly earthy luster, and fine-grained volcanic texture; typical hardness is about 5–6 Mohs, with no obvious cleavage. The specimen appears strongly weathered and may contain rusty iron-oxide staining.
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Physical properties
Dark gray-brown, highly vesicular, dull to slightly earthy luster, and fine-grained volcanic texture; typical hardness is about 5–6 Mohs, with no obvious cleavage. The specimen appears strongly weathered and may contain rusty iron-oxide staining.
Formation & geological history
Forms when gas-rich basaltic or andesitic lava cools rapidly at or near the surface, trapping bubbles; commonly Quaternary to modern in age. Weathering can lighten the surface and obscure its original color.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, and sometimes abrasive media; generally not suitable for fine jewelry. Small attractive pieces have modest collector interest.
Geological facts
Scoria is denser and usually darker than pumice, though heavily weathered examples can resemble porous slag or tuff. Vesicles are irregular, natural cavities produced by escaping volcanic gases.
Field identification & locations
Identify it by its irregular holes, rough volcanic surface, and lack of glassy or metallic appearance; common near cinder cones, lava flows, and volcanic fields worldwide. A definitive identification would require density, thin-section, or chemical testing.
