igneous
Scoria (vesicular basalt)
Vesicular basalt; chiefly plagioclase, pyroxene, and iron-rich glass
AI-generated identification · may be incorrectDark gray to black, highly vesicular, dull to slightly glassy luster, fine-grained volcanic texture; hardness about 5–6 Mohs, no visible cleavage, and relatively low density from abundant gas cavities.
Identified More igneous →
Explore Scoria (vesicular basalt) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray to black, highly vesicular, dull to slightly glassy luster, fine-grained volcanic texture; hardness about 5–6 Mohs, no visible cleavage, and relatively low density from abundant gas cavities.
Formation & geological history
Forms when gas-rich basaltic lava erupts and rapidly cools, preserving bubbles as vesicles; commonly associated with geologically young volcanic cones, lava flows, and cinder deposits, though it can form at any volcanic age.
Uses & applications
Used as lightweight aggregate, drainage and landscaping stone, abrasive material, and occasionally in decorative specimens; generally not a jewelry gemstone.
Geological facts
Its reddish or black color reflects oxidation and iron content. It differs from pumice because scoria is typically darker, denser, and has thicker vesicle walls.
Field identification & locations
Identify it by its rough, porous surface, dark basaltic color, and heavier feel than pumice; common near basaltic volcanoes such as Hawaii, Iceland, the Cascades, and the Andes.
