igneous
Scoria (vesicular basalt)
Scoria; iron-rich vesicular basalt, primarily plagioclase, pyroxene, and olivine
AI-generated identification · may be incorrectTypically dark red-brown to black, highly vesicular, with dull to slightly glassy luster; hardness about 5–6 Mohs, no prominent cleavage, and low-to-moderate density due to abundant gas bubbles. The specimen’s reddish color reflects oxidation of iron-bearing minerals.
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
Typically dark red-brown to black, highly vesicular, with dull to slightly glassy luster; hardness about 5–6 Mohs, no prominent cleavage, and low-to-moderate density due to abundant gas bubbles. The specimen’s reddish color reflects oxidation of iron-bearing minerals.
Formation & geological history
Forms when gas-rich basaltic lava erupts and rapidly cools, trapping bubbles; oxidation commonly occurs in subaerial volcanic environments. It may range from recent Holocene volcanic material to much older volcanic deposits.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, abrasive, and decorative rock; occasionally collected as a volcanic specimen. It has little jewelry value.
Geological facts
Scoria is denser and generally darker than pumice, whose glassy silica-rich composition makes it lighter and often pale. Vesicles are irregular and usually larger and more open than pores in ordinary basalt.
Field identification & locations
Identify it by its rusty red-black color, rough frothy surface, angular cavities, and lightweight feel; common sources include volcanic fields, cinder cones, and lava flows worldwide. Value is typically $3–$15 for a hand specimen, or up to $20–$40 for unusually large or attractive pieces.
