sedimentary

Rounded sandstone pebble

Quartz-rich sandstone, likely arenite

AI-generated identification · may be incorrect

Fine-grained, brown to reddish-brown, dull earthy luster, and smoothly rounded from abrasion; chiefly quartz with possible feldspar, iron oxides, and clay. Typical hardness is about 6–7 for quartz grains, though the cement may be softer; no visible cleavage or crystals.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand was compacted and cemented by silica, calcite, or iron oxides, commonly in river, beach, dune, or shallow-marine environments. The rounded shape indicates later transport and abrasion; its exact geological age cannot be determined from the image.

Uses & applications

Used as aggregate, paving and landscaping stone, and occasionally as a decorative or teaching specimen; generally not suitable for jewelry.

Geological facts

The surface texture and rounded outline are consistent with a naturally tumbled pebble, though a manufactured abrasive stone is also possible without scale or testing.

Field identification & locations

Common in streambeds, beaches, glacial deposits, and sedimentary outcrops worldwide. Identify by grainy texture, visible sand-sized particles, and a streak or fresh break showing quartz-rich grains; acid testing can detect calcareous cement.