igneous
Vesicular volcanic rock, likely weathered scoria
Scoria (vesicular basaltic-andesitic volcanic rock), composition approximately plagioclase, pyroxene, and volcanic glass
AI-generated identification · may be incorrectLow-density, porous texture with abundant rounded vesicles; brown to dark gray, earthy surface, generally dull to slightly glassy. Typical hardness is about 5–6 Mohs, with no prominent cleavage and an iron-rich, weathered matrix.
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Physical properties
Low-density, porous texture with abundant rounded vesicles; brown to dark gray, earthy surface, generally dull to slightly glassy. Typical hardness is about 5–6 Mohs, with no prominent cleavage and an iron-rich, weathered matrix.
Formation & geological history
Formed when gas-rich lava erupted and rapidly cooled, trapping bubbles; the brown color reflects oxidation and weathering. It is generally Quaternary to geologically young, though similar scoria occurs throughout volcanic provinces of many ages.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasive material, drainage medium, and sometimes in decorative specimen collections; it is not normally a jewelry material.
Geological facts
The holes are vesicles, originally bubbles in molten lava, rather than fossils. Pale patches may be weathered feldspar or secondary minerals; the specimen could also be porous volcanic tuff, but its texture most strongly suggests scoria.
Field identification & locations
Identify it by very high vesicularity, low weight, irregular rough surfaces, and volcanic minerals; distinguish it from pumice because scoria is typically darker, denser, and less frothy. Common around basaltic volcanoes and cinder cones worldwide.
