sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, commonly arkose or lithic sandstone

AI-generated identification · may be incorrect

Fine- to medium-grained, tan, porous, and dull to slightly gritty; composed mainly of quartz with feldspar and rock fragments cemented by silica, calcite, or iron oxides. Typical hardness is about 6–7 for quartz grains, but the rock is relatively friable; no visible cleavage and usually clastic granular texture.

Identified August 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from sand deposited, compacted, and cemented in rivers, beaches, dunes, or shallow seas, then rounded by prolonged water transport and abrasion. Its exact geological age cannot be determined from the photograph and may range from recent sediment to ancient bedrock-derived gravel.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and occasionally decorative material; this small rounded pebble has little commercial value but may be useful for teaching or collecting.

Geological facts

The rounded shape and smoothed surface indicate erosion and transport, while its abundant visible grains identify it as clastic rather than crystalline igneous rock.

Field identification & locations

Identify it by its gritty sand-sized grains, porous tan surface, and lack of large interlocking crystals; a glassy scratch test may reveal quartz, though cement strength varies. Sandstone gravels occur widely in riverbeds, beaches, and glacial deposits.