sedimentary

Rounded weathered stone, likely sandstone or chert

Indeterminate; probable quartz-rich clastic rock (sandstone) or microcrystalline silica (chert)

AI-generated identification · may be incorrect

Tan-brown, dull to weakly earthy luster, smoothly rounded and fine-grained; apparent hardness is roughly 5–7 Mohs, but cleavage and specific gravity cannot be determined from the image.

Identified August 16, 2026More sedimentary →

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Physical properties

Tan-brown, dull to weakly earthy luster, smoothly rounded and fine-grained; apparent hardness is roughly 5–7 Mohs, but cleavage and specific gravity cannot be determined from the image.

Formation & geological history

Likely a naturally water-worn pebble formed from sedimentary material, then rounded by stream, beach, or glacial transport; its exact geological age and formation cannot be established visually.

Uses & applications

Commonly collected as a decorative or teaching specimen; typically has negligible commercial value unless testing reveals unusual composition or provenance.

Geological facts

The smooth shape indicates prolonged abrasion, while the pale tan coloration may reflect iron staining, carbonate cement, or weathered silica-rich material.

Field identification & locations

Test streak, hardness, and acid reaction: sandstone feels granular and may scratch glass variably; chert is very hard, nonporous, and can scratch glass; limestone fizzes with dilute hydrochloric acid. Similar pebbles occur worldwide in river gravels and beaches.