sedimentary

Tumbled brown pebble

Indeterminate; likely quartz-rich sandstone or chert

AI-generated identification · may be incorrect

Small, rounded, matte brown specimen with fine-grained texture; likely Mohs hardness ~6–7 if chert, or ~5–7 if sandstone. Crystal structure and cleavage are not visible; specific gravity is approximately 2.3–2.7.

Identified August 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Its smooth shape indicates natural water abrasion or tumbling. If sandstone, it formed from lithified sand; if chert, from microcrystalline silica replacing sediment, potentially at various geological ages.

Uses & applications

Suitable as a decorative pebble, craft material, or educational specimen; not identifiable as a gemstone-grade material from the image. Commercial value is minimal.

Geological facts

The uniform brown color may result from iron-oxide staining. A glass-scratching test can distinguish harder chert from softer sandstone, though it may damage the specimen.

Field identification & locations

Common in stream gravels, beaches, landscaping stone, and rock-tumbling mixes. Look for visible sand grains and weak scratching ability in sandstone, versus a smooth waxy surface and strong glass-scratching ability in chert.