mineral

Rounded quartz-rich pebble

Likely microcrystalline quartz (chalcedony), possibly weathered quartzite

AI-generated identification · may be incorrect

Opaque gray-brown, weakly translucent edges, dull to waxy luster, and irregular granular texture; quartz hardness is about 7 Mohs, with no cleavage and conchoidal fracture. The dark surface patches may be iron/manganese staining or attached matrix.

Identified August 21, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed as silica-rich material in a vein, volcanic setting, or metamorphic rock, then rounded by stream or beach abrasion; its exact geological age and identity cannot be established from the photograph alone.

Uses & applications

Common material has little commercial value, but attractive chalcedony and quartzite are used for cabochons, carvings, ornaments, and occasionally aggregate or building stone.

Geological facts

Chalcedony is fibrous microcrystalline quartz, while quartzite is metamorphosed sandstone; both can look similar when weathered and rounded.

Field identification & locations

Test an inconspicuous spot with a steel file: quartz-rich material should resist scratching, while glassy streaks or softer surfaces suggest another rock. Commonly found in stream gravels, beaches, and weathered vein deposits.