igneous
Scoria (vesicular basalt)
Vesicular basalt, chiefly plagioclase, pyroxene, and iron-rich glass
AI-generated identification · may be incorrectHardness about 5–6 Mohs; reddish-brown to black, dull to slightly vitreous, highly vesicular, with no obvious cleavage and low-to-moderate specific gravity. The abundant holes formed from trapped volcanic gas.
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
Hardness about 5–6 Mohs; reddish-brown to black, dull to slightly vitreous, highly vesicular, with no obvious cleavage and low-to-moderate specific gravity. The abundant holes formed from trapped volcanic gas.
Formation & geological history
An extrusive volcanic rock formed when gas-rich basaltic lava cooled rapidly, commonly during cinder-cone or lava-fountaining eruptions. Its exact age cannot be determined from the image; scoria ranges from modern to Precambrian.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, abrasives, and occasionally decorative objects; generally not used as a gemstone.
Geological facts
The red color commonly results from oxidation of iron during or after eruption. Scoria is denser and darker than pumice and typically has thicker, more interconnected-looking vesicle walls.
Field identification & locations
Identify it by its rough, frothy texture, angular vesicles, reddish-black color, and relatively heavy feel compared with pumice; a streak and hand-lens inspection can help distinguish it from slag. Common near basaltic volcanoes and cinder cones worldwide.
