sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, likely arenite

AI-generated identification · may be incorrect

Fine-grained, tan-brown, dull earthy luster, and well-rounded from abrasion; typically Mohs hardness 6–7 for quartz grains but relatively friable as a rock. Composed mainly of quartz with variable feldspar, clay, and iron-oxide cement; no visible crystals or cleavage.

Identified August 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Lithified sand deposited in a river, beach, dune, or shallow-marine environment, then compacted and cemented over geologic time. The smooth oval shape indicates prolonged transport or wave abrasion; exact age cannot be determined from the image.

Uses & applications

Used as aggregate, building stone, landscaping material, and occasionally as a naturally shaped decorative or craft stone; this ordinary pebble has little jewelry value.

Geological facts

Its rounded shape reflects mechanical weathering rather than crystal growth. A dilute acid test is usually negative unless substantial carbonate cement is present.

Field identification & locations

Common in streambeds, beaches, gravel deposits, and weathered sandstone terrains. Identify it by gritty texture, visible sand-sized grains under magnification, lack of vesicles, and possible scratching by quartz or glass.