igneous
Vesicular basalt pebble
Vesicular basalt, a fine-grained volcanic rock composed mainly of plagioclase, pyroxene, and commonly olivine
AI-generated identification · may be incorrectPale yellow-tan, rounded pebble with numerous small, rounded vesicles; dull to slightly earthy luster. Basalt is typically Mohs 5–6, with a fine-grained structure and no visible cleavage; the light color may reflect weathering or surface coating.
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Physical properties
Pale yellow-tan, rounded pebble with numerous small, rounded vesicles; dull to slightly earthy luster. Basalt is typically Mohs 5–6, with a fine-grained structure and no visible cleavage; the light color may reflect weathering or surface coating.
Formation & geological history
Formed when gas-rich basaltic lava cooled quickly, trapping bubbles as vesicles. Its precise age and locality cannot be determined from the image; basalt forms in volcanic settings from recent eruptions to rocks billions of years old.
Uses & applications
Basalt is widely used as crushed aggregate, road stone, and building material; this small vesicular pebble is mainly suitable for collecting or display.
Geological facts
Vesicles are former gas bubbles preserved in solidified lava; weathering can discolor basalt from its usual dark gray or black to lighter shades.
Field identification & locations
Look for rounded bubble cavities in a dense, fine-grained volcanic matrix; confirm basalt by mineral or chemical examination, since the photo alone cannot establish the rock definitively. Basalt occurs worldwide in volcanic regions and as river or beach pebbles.
