sedimentary

Rounded quartz-rich pebble, likely sandstone or granitic-derived pebble

Indeterminate clastic rock; likely quartz-rich sandstone/conglomerate clast

AI-generated identification · may be incorrect

Small, smoothly water-worn, tan-gray pebble with a dull earthy-to-satin luster and fine granular texture. Likely Mohs 6–7 if quartz-rich; no visible cleavage or crystal faces. Exact composition cannot be confirmed from the photograph.

Identified September 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Probably weathered from local sedimentary or granitic terrain and rounded by stream, beach, or wave transport. Near 34.9°N, 120.4°W, coastal and alluvial transport is plausible; geological age is indeterminate.

Uses & applications

Primarily a natural curiosity or paperweight; unexceptional pebbles have no commercial jewelry or construction value.

Geological facts

The smooth oval shape records abrasion during transport, while the tan color may reflect iron-oxide staining. A close inspection or fresh chip is needed to distinguish sandstone from altered granite, chert, or a volcanic pebble.

Field identification & locations

Likely identification tests: glass-scratch test (quartz-rich material should scratch glass), acid test for carbonate cement, and a hand lens to inspect grains. Commonly found in California beaches, stream gravels, and road cuts.