sedimentary

Assorted polished river pebbles

Mixed lithologies, likely quartzite, chert, jasper, and weathered igneous/metamorphic rocks

AI-generated identification · may be incorrect

Rounded, tumbled stones with gray, brown, cream, black, and translucent colors; surfaces are mostly dull to waxy or vitreous. Typical hardness is about 6–7 Mohs for quartz-rich pieces, with variable cleavage and specific gravity around 2.5–2.8.

Identified September 19, 2026More sedimentary →

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Physical properties

Formation & geological history

These are likely naturally water-rounded alluvial or beach pebbles, later polished or tumbled; their ages depend on the source rocks and may range from ancient Precambrian to younger formations.

Uses & applications

Used for landscaping, crafts, decorative bowls, aquariums, and inexpensive lapidary pieces; translucent or patterned examples may be sold as cabochon material.

Geological facts

The image shows a group rather than one identifiable species; exact identification requires separate examination, hardness testing, streak, and ideally a loupe or thin section.

Field identification & locations

Quartzite/chert commonly show hardness near 7 and resist scratching by steel; jasper is opaque and fine-grained, while quartz-rich stones may scratch glass. Common worldwide in river gravels, beaches, and glacial deposits.