igneous
Vesicular basalt (scoria-like lava rock)
Basalt, predominantly plagioclase + pyroxene ± olivine; vesicles formed by trapped volcanic gas
AI-generated identification · may be incorrectDark gray to brown, fine-grained, dull to slightly glassy, with abundant rounded pores; typically Mohs 5–6, no visible cleavage, and specific gravity about 2.5–3.0 (lower when highly vesicular).
Identified More igneous →
Explore Vesicular basalt (scoria-like lava rock) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark gray to brown, fine-grained, dull to slightly glassy, with abundant rounded pores; typically Mohs 5–6, no visible cleavage, and specific gravity about 2.5–3.0 (lower when highly vesicular).
Formation & geological history
Extrusive volcanic rock formed when basaltic lava cooled rapidly at or near the surface, commonly during eruptions within the Cenozoic or older volcanic episodes.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, and occasionally in decorative collections; generally not a gemstone.
Geological facts
The cavities are vesicles, not fossils; reddish-brown areas commonly reflect oxidation of iron-bearing minerals. Its compact, rounded form may indicate natural abrasion or tumbling.
Field identification & locations
Identify by its dark basaltic color, fine texture, and gas bubbles; scoria is usually redder and lighter, while basalt is denser and darker. Common in volcanic regions such as Hawaii, Iceland, Japan, and western North America.
