sedimentary

Rounded quartz-rich pebble

Chert or quartzite pebble (indeterminate from image)

AI-generated identification · may be incorrect

Tan, opaque, fine-grained, and smoothly water-worn with a dull to faintly waxy luster; likely hardness about 6.5–7 Mohs. No visible cleavage or crystals; specific gravity likely around 2.6.

Identified September 16, 2026More sedimentary →

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Physical properties

Tan, opaque, fine-grained, and smoothly water-worn with a dull to faintly waxy luster; likely hardness about 6.5–7 Mohs. No visible cleavage or crystals; specific gravity likely around 2.6.

Formation & geological history

Probably a naturally rounded fragment transported by river, beach, or glacial action. Its source rock may be chert (silica-rich sedimentary rock) or quartzite (metamorphosed sandstone), generally formed from Precambrian to younger sediments.

Uses & applications

Commonly used as decorative gravel, landscaping stone, teaching specimens, and occasionally in lapidary work. This ordinary pebble has little commercial value.

Geological facts

The tan color may result from iron-oxide staining or weathering. A steel knife should not scratch it easily, while it may scratch ordinary glass.

Field identification & locations

Look for glassy silica, lack of cleavage, and a conchoidal fracture; acid testing is usually nonreactive. Common in streambeds, beaches, gravel deposits, and glacial till worldwide.