igneous
Vesicular basalt (scoria-like volcanic rock)
Vesicular basalt; predominantly plagioclase, pyroxene, and volcanic glass, with possible iron oxides
AI-generated identification · may be incorrectLight gray to brown, highly vesicular, dull to slightly glassy luster, irregular fracture, and no obvious cleavage; hardness about 5–6, with low-to-moderate specific gravity due to abundant cavities.
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Physical properties
Light gray to brown, highly vesicular, dull to slightly glassy luster, irregular fracture, and no obvious cleavage; hardness about 5–6, with low-to-moderate specific gravity due to abundant cavities.
Formation & geological history
Formed when gas-rich basaltic lava cooled rapidly, trapping bubbles; its exact geological age cannot be determined from the photograph. Commonly associated with young volcanic cones, lava flows, and cinder deposits.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasives, and occasionally as a specimen; generally not a jewelry material.
Geological facts
The cavities are vesicles formed by escaping volcanic gases. The pale, weathered surface and metallic-looking patches may reflect alteration or iron-oxide staining rather than valuable metal.
Field identification & locations
Identify by its frothy texture, numerous rounded holes, dark basaltic groundmass, and low density; distinguish it from pumice, which is usually much lighter and commonly floats. Typical localities include Hawaii, Iceland, Italy, Mexico, and volcanic regions worldwide.
