igneous
Rounded volcanic scoria or vesicular basalt pebble
Vesicular basalt, likely altered; predominantly plagioclase, pyroxene, and iron oxides
AI-generated identification · may be incorrectLight tan-gray, fine-grained and rounded, with numerous small dark vesicles or weathered cavities; likely Mohs 5–6, dull to slightly earthy luster, massive texture, and no visible cleavage. The smooth shape indicates water abrasion or deliberate tumbling.
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Physical properties
Light tan-gray, fine-grained and rounded, with numerous small dark vesicles or weathered cavities; likely Mohs 5–6, dull to slightly earthy luster, massive texture, and no visible cleavage. The smooth shape indicates water abrasion or deliberate tumbling.
Formation & geological history
Formed when basaltic lava cooled rapidly while escaping gas created vesicles, probably during Cenozoic volcanic activity; subsequent weathering and stream or beach transport rounded it. Exact age and locality cannot be determined from the image.
Uses & applications
Commonly used as landscaping or decorative stone and occasionally as a lapidary specimen; it has little jewelry value unless unusually attractive or polished.
Geological facts
The pale surface may reflect weathering, alteration, or a carbonate coating rather than the rock’s fresh color. Vesicles distinguish it from most dense basalt, though the cavities here appear partly filled or weathered.
Field identification & locations
Look for a dark mafic interior, fine grain, irregular pores, and a relatively low density; a streak, acid, or density test would help separate it from limestone or concrete. Common around volcanic regions and gravels.
