igneous
Dark, vesicular volcanic rock (likely basalt or scoria)
Basaltic scoria; predominantly plagioclase, pyroxene, and iron-rich oxides
AI-generated identification · may be incorrectDark gray-brown, fine-grained and lumpy, with tiny reflective mineral grains and possible vesicles. Typical hardness is about 5–6 Mohs; generally dull to weakly vitreous, with no obvious cleavage and moderate density (scoria is relatively lightweight).
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Physical properties
Dark gray-brown, fine-grained and lumpy, with tiny reflective mineral grains and possible vesicles. Typical hardness is about 5–6 Mohs; generally dull to weakly vitreous, with no obvious cleavage and moderate density (scoria is relatively lightweight).
Formation & geological history
An extrusive igneous rock formed when basaltic lava cooled rapidly; trapped gas may produce its vesicular texture. Such rocks are commonly Quaternary to recent, though older examples occur wherever ancient volcanic flows or cinders are exposed.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasives, and occasionally in concrete or thermal insulation. Attractive pieces may be collected, but this specimen appears ordinary and unpolished.
Geological facts
The image supports a volcanic identification but cannot reliably distinguish dense basalt from scoria. A streak test, density test, and close inspection for pores would improve confidence.
Field identification & locations
Common in volcanic regions, including Hawaii, Iceland, the western United States, Mexico, Italy, and Japan. Basalt is heavy and compact; scoria is noticeably porous and may have reddish-brown oxidized surfaces.
