sedimentary

Tumbled sandstone or weathered limestone pebble

Likely quartz-rich sandstone (SiO₂) or calcarenite/limestone (CaCO₃)

AI-generated identification · may be incorrect

Pale tan, fine-grained, dull to softly earthy luster, rounded by abrasion; likely Mohs 3–7 depending on composition, with no visible crystals or cleavage. The image cannot distinguish sandstone from limestone confidently.

Identified August 25, 2026More sedimentary →

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Physical properties

Formation & geological history

A sedimentary pebble formed from cemented sand or carbonate sediment, then rounded by stream, beach, or glacial transport; its exact geological age and source are indeterminate.

Uses & applications

Commonly used as landscaping, aggregate, and building stone; attractive pieces may be collected or used in crafts, though this specimen has little commercial value.

Geological facts

A drop of dilute hydrochloric acid will fizz noticeably if it is limestone or calcarenite; sandstone generally does not fizz. A glass-scratch test can indicate quartz-rich sandstone, though surface weathering may affect results.

Field identification & locations

Look for gritty grains and weak/no acid reaction for sandstone, or a chalky texture and acid fizz for limestone. Tan rounded pebbles of both types are widespread in riverbeds, beaches, fields, and glacial deposits.