sedimentary

Rounded gray pebble

Likely quartz-rich chert or fine-grained quartzite; exact identification is uncertain from the photograph

AI-generated identification · may be incorrect

Smooth, water-worn, gray-green surface with dull to weakly waxy luster and fine grain; likely hardness about 6.5–7 Mohs, with no visible cleavage. The pale speckling may indicate quartz grains or weathering.

Identified August 30, 2026More sedimentary →

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Physical properties

Formation & geological history

Probably formed as silica-rich sediment that lithified and/or recrystallized, then was rounded by stream or beach transport; age and original locality cannot be determined visually.

Uses & applications

Suitable as a decorative pebble, craft material, or teaching specimen; if quartzite, it has construction value in aggregate and dimension stone, while chert is used for tools and aggregate.

Geological facts

A steel file or knife should not easily scratch quartz-rich material; testing for a white streak, translucency at thin edges, and conchoidal fracture can help distinguish chert from quartzite.

Field identification & locations

Common in river gravels, beaches, glacial deposits, and weathered quartz-bearing terrains worldwide. Confirm with a hardness test and close examination of grain size; avoid destructive testing if it is a valued find.