sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, likely arkosic or lithic sandstone

AI-generated identification · may be incorrect

Tan-brown, fine-grained, matte to faintly earthy luster, with rounded edges from abrasion; chiefly quartz with feldspar and rock fragments cemented by silica, calcite, or iron oxides. Typical hardness is about 6–7 for grains, though the rock may scratch unevenly; no visible cleavage or crystals.

Identified September 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand accumulated, compacted, and cemented in a river, beach, dune, or shallow-marine environment, generally over millions to hundreds of millions of years. Its smooth shape indicates later water or shoreline abrasion, or deliberate tumbling.

Uses & applications

Used as building stone, aggregate, landscaping material, and occasionally as a decorative or massage stone; this specimen has little jewelry value.

Geological facts

The rounded outline and uniform surface may reflect natural stream wear or human polishing. A streak or fresh chip would better reveal grain size and cement type.

Field identification & locations

Common worldwide, especially in sedimentary basins and river gravels. Look for visible sand grains, a gritty texture, and possible fizz with dilute hydrochloric acid if calcite-cemented; value is typically $1–$10, or up to about $20 for an attractive polished specimen.