sedimentary

Tumbled brown jasper or chert pebble

Microcrystalline quartz (SiO₂), likely jasper/chert

AI-generated identification · may be incorrect

Opaque reddish-brown, fine-grained, waxy to slightly glassy luster, and rounded by abrasion or tumbling. Mohs hardness about 6.5–7; no visible cleavage; specific gravity about 2.6.

Identified August 16, 2026More sedimentary →

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Physical properties

Opaque reddish-brown, fine-grained, waxy to slightly glassy luster, and rounded by abrasion or tumbling. Mohs hardness about 6.5–7; no visible cleavage; specific gravity about 2.6.

Formation & geological history

Forms when silica-rich groundwater replaces or cements sediments, commonly during diagenesis; its exact geological age cannot be determined from the image. The smooth shape indicates stream wear or artificial tumbling.

Uses & applications

Used for inexpensive cabochons, beads, tumbled stones, carvings, and decorative aggregate. It has modest collector value unless showing rare patterns or provenance.

Geological facts

Jasper is an opaque variety of microcrystalline quartz, while chert is the broader fine-grained silica category; visual separation can require a hardness or chemical test.

Field identification & locations

Look for opacity, very fine texture, earthy red-brown color, and resistance to scratching by steel; quartz should not scratch it. Common in sedimentary terrains and gravel deposits worldwide.