sedimentary

Tumbled sandstone pebble

Quartz-rich sandstone, commonly subarkose or arkose

AI-generated identification · may be incorrect

Typically 6–7 Mohs for quartz grains, with softer cement; tan, reddish-brown, cream, earthy luster, and visible layered or wavy sedimentary texture. Composed mainly of quartz with feldspar and iron-oxide cement; porous, with no consistent cleavage.

Identified August 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand was deposited, compacted, and cemented in an ancient river, beach, dune, or shallow-marine environment; iron oxidation produces the reddish color. The exact geological age cannot be determined from the photograph, and later stream abrasion rounded the specimen.

Uses & applications

Used widely as building stone, paving, aggregate, and decorative landscaping material; attractive pieces may be polished or sold as curios and display stones.

Geological facts

The concentric-looking bands are likely bedding, cross-bedding, or iron-stained cement rather than crystal growth. Sandstone can preserve ripple marks, ancient dunes, and other sedimentary structures.

Field identification & locations

Identify by gritty texture, visible sand grains, layered coloration, and lack of glassy crystal faces; it should usually scratch glass if quartz-rich. Common in sedimentary terrains and streambeds worldwide; vinegar typically causes no reaction unless carbonate cement is present.