igneous
Vesicular volcanic pebble, likely pumice or vesicular andesite
Pumice (volcanic glass) or vesicular andesite; exact identification requires examination
AI-generated identification · may be incorrectLight gray, rounded pebble with abundant small cavities (vesicles) and a dull, rough surface. Pumice is typically glassy and Mohs 5–6; andesite is commonly Mohs 5–6, with hardness varying by mineral content.
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Physical properties
Light gray, rounded pebble with abundant small cavities (vesicles) and a dull, rough surface. Pumice is typically glassy and Mohs 5–6; andesite is commonly Mohs 5–6, with hardness varying by mineral content.
Formation & geological history
Formed when gas-rich volcanic lava cooled rapidly, trapping bubbles; the image does not establish its age or precise composition. Rounded shape suggests transport and abrasion by water or sediment.
Uses & applications
Pumice is used as an abrasive, lightweight aggregate, and horticultural medium; andesite is used as construction aggregate and dimension stone. This small pebble is mainly of collecting interest.
Geological facts
Vesicles record gas escaping or trapped during volcanic eruption. Pumice can be so porous that some pieces float, though this pebble’s density cannot be determined visually.
Field identification & locations
Look for a very low weight and a frothy, glassy texture to distinguish pumice; denser, visibly crystalline material favors vesicular andesite. Volcanic pebbles occur near volcanic regions and in river or beach deposits.
