igneous
Weathered vesicular volcanic rock, likely scoria
Scoria (vesicular basaltic-andesite), compositionally dominated by plagioclase, pyroxene, and iron-rich glass
AI-generated identification · may be incorrectDark tan-brown, highly porous, dull to slightly earthy luster, with irregular vesicles and no obvious cleavage; typical hardness about 5–6 Mohs and specific gravity roughly 2.0–2.8, though weathering may lighten it.
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Physical properties
Dark tan-brown, highly porous, dull to slightly earthy luster, with irregular vesicles and no obvious cleavage; typical hardness about 5–6 Mohs and specific gravity roughly 2.0–2.8, though weathering may lighten it.
Formation & geological history
Formed when gas-rich mafic lava cooled rapidly, trapping bubbles; the rusty coloration likely reflects oxidation of iron-bearing minerals during weathering. Its precise geological age cannot be determined from the photograph.
Uses & applications
Used as lightweight aggregate, drainage material, landscaping stone, and abrasive; attractive pieces may be collected but are generally not jewelry grade.
Geological facts
Scoria is denser and darker than pumice because it contains more iron and less total pore space; weathered scoria can become brown, yellow, or orange.
Field identification & locations
Common around basaltic cinder cones, lava flows, and volcanic fields worldwide. Identify it by abundant irregular holes, rough texture, and volcanic appearance; confirm with a fresh surface and lack of sedimentary layering.
