sedimentary

Rounded sandstone pebble

Quartz-rich sandstone (primarily SiO₂), possibly arkosic sandstone

AI-generated identification · may be incorrect

Fine- to medium-grained, tan to reddish-brown, matte and granular; composed mainly of quartz with feldspar and iron-oxide cement. Hardness is typically 6–7 for grains but variable overall; no visible cleavage, porous texture, and moderate specific gravity around 2.2–2.7.

Identified August 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Lithified sand deposited in a river, beach, dune, or shallow-marine environment, then naturally rounded by abrasion during transport. Its exact geological age cannot be determined from the image and may range from recent lithification to hundreds of millions of years.

Uses & applications

Commonly used as aggregate, building stone, paving, landscaping material, and occasionally in decorative crafts; this ordinary pebble has little jewelry value.

Geological facts

The rounded shape indicates substantial transport or wave abrasion. Iron oxides produce the warm tan and rusty coloration, while weathering can accentuate surface pores.

Field identification & locations

Identify it by visible sand-sized grains, gritty texture, lack of interlocking crystals, and possible layering or iron staining; it should not fizz strongly in dilute hydrochloric acid. Sandstone pebbles are common in streambeds, beaches, deserts, and glacial deposits.