sedimentary

Rounded sandstone pebble

Quartz-rich sandstone (likely arkosic or lithic sandstone)

AI-generated identification · may be incorrect

Fine- to medium-grained, tan-brown rock with a dull, granular surface and rounded water-worn shape; mainly quartz with feldspar and rock fragments, cemented by silica, calcite, or iron oxides. Typical hardness is about 6–7 Mohs for the grains, with no obvious cleavage; specific gravity is roughly 2.2–2.7.

Identified August 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from sand deposited, compacted, and cemented in a river, beach, dune, or basin environment, then rounded by erosion and transport. Its exact geological age cannot be determined from the photograph and may range from recent sediment to ancient bedrock.

Uses & applications

Common sandstone is used for building stone, paving, landscaping, aggregate, and historically carving; ordinary rounded pebbles have little commercial value.

Geological facts

The rusty tan coloration likely reflects iron-oxide coatings or cement. Individual grains and bedding are difficult to see because the specimen is heavily weathered and rounded.

Field identification & locations

Look for gritty texture, visible sand-sized grains, and possible effervescence if calcite-cemented; a glassy scratch test can help distinguish quartz-rich grains. Common worldwide in streambeds, beaches, and sandstone outcrops.