igneous
Vesicular basalt (likely scoria)
Vesicular basalt; predominantly plagioclase, pyroxene, and Fe-Mg oxides
AI-generated identification · may be incorrectDark gray, highly vesicular, and dull to slightly glassy; typically Mohs 5–6, fine-grained, with little cleavage and specific gravity about 2.4–2.9. The abundant cavities formed from trapped gas bubbles.
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Physical properties
Dark gray, highly vesicular, and dull to slightly glassy; typically Mohs 5–6, fine-grained, with little cleavage and specific gravity about 2.4–2.9. The abundant cavities formed from trapped gas bubbles.
Formation & geological history
An extrusive volcanic rock formed when basaltic lava cooled rapidly at or near the surface, commonly during the Cenozoic or younger volcanic activity. Its exact age and locality cannot be determined from the image.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasive, and occasionally in construction; scoria is also popular as a decorative specimen. It has little jewelry value.
Geological facts
The specimen’s vesicles are elongated and irregular, consistent with scoria or vesicular basalt; unusually pale or rusty cavities may contain secondary minerals such as zeolites or calcite.
Field identification & locations
Identify it by its dark mafic color, abundant holes, rough texture, and lack of layering; it is generally heavier than pumice and does not usually float. Common in volcanic fields, lava flows, cinder cones, and basalt quarries.
