sedimentary

Rounded sandstone cobble

Quartz-rich sandstone (likely arkose or litharenite)

AI-generated identification · may be incorrect

Hardness about 6–7 for quartz grains; tan-gray, dull to slightly gritty, fine- to medium-grained, with no obvious cleavage. The rounded shape and matte surface indicate prolonged stream or beach abrasion; exact composition cannot be confirmed from the image alone.

Identified August 15, 2026More sedimentary →

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Physical properties

Formation & geological history

Cemented sand accumulated in an ancient river, beach, dune, or basin and lithified through compaction and mineral cementation. Its geological age is indeterminate without locality and laboratory analysis; subsequent transport rounded it into a cobble.

Uses & applications

Common sandstone is used as building stone, aggregate, paving material, and occasionally as a decorative or educational specimen. This nondescript cobble has little commercial or jewelry value.

Geological facts

Sandstone commonly contains quartz and feldspar grains bound by silica, calcite, or iron oxides; the tan color may reflect iron-bearing cement. It may weather into rounded cobbles in active streams.

Field identification & locations

Look for visible sand grains, gritty texture, and layering or cemented fragments; a streak, acid test, hand lens, and hardness test help distinguish it from limestone, quartzite, or concrete. Common worldwide in riverbeds and sedimentary terrains.