igneous
Vesicular basalt (likely scoria)
Basaltic volcanic rock; predominantly plagioclase, pyroxene, and olivine with volcanic glass
AI-generated identification · may be incorrectDark gray-black, fine-grained, matte to slightly glassy, with rounded gas vesicles; hardness about 5–6 Mohs, no obvious cleavage, and typical specific gravity around 2.4–2.8, though vesicles reduce bulk density.
Identified More igneous →
Explore Vesicular basalt (likely scoria) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray-black, fine-grained, matte to slightly glassy, with rounded gas vesicles; hardness about 5–6 Mohs, no obvious cleavage, and typical specific gravity around 2.4–2.8, though vesicles reduce bulk density.
Formation & geological history
Formed when fluid basaltic lava cooled rapidly at or near the surface, trapping gas bubbles; commonly Quaternary to recent, although basalt occurs throughout geologic time.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasives, and occasionally in decorative specimens; generally low jewelry value.
Geological facts
The highly bubbly, rough variety is called scoria; denser, finer-grained vesicular material may be termed vesicular basalt. Some cavities can later host zeolite or calcite crystals.
Field identification & locations
Common in volcanic regions, including Hawaii, Iceland, the western United States, Mexico, and oceanic islands. Identify it by its black basaltic color, fine texture, and irregular vesicles; it is unlike porous pumice, which is much lighter and often pale.
