sedimentary

Tumbled brown stone, likely chert or jasper

Microcrystalline quartz (SiO₂), probable chert/jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown to gray-brown, opaque, waxy to dull luster, very fine-grained with no visible cleavage. The smoothly rounded shape indicates natural water wear or tumbling.

Identified August 25, 2026More sedimentary →

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Physical properties

Hardness about 6.5–7 Mohs; brown to gray-brown, opaque, waxy to dull luster, very fine-grained with no visible cleavage. The smoothly rounded shape indicates natural water wear or tumbling.

Formation & geological history

Likely formed when silica-rich groundwater replaced or cemented sediment, producing microcrystalline quartz; exact age cannot be determined visually. Brown coloration commonly comes from iron oxides and other impurities.

Uses & applications

Used for lapidary items, cabochons, carvings, ornaments, and historically as a toolmaking stone. This small rounded specimen has modest decorative value.

Geological facts

Chert and jasper are varieties of microcrystalline quartz; jasper is typically more opaque and iron-rich. A steel file generally will not scratch it, while quartz or hardened steel may scratch glass.

Field identification & locations

Common in river gravels and sedimentary terrains worldwide, including the United States, Mexico, India, and Australia. Confirm with a streak, hardness, and conchoidal-fracture test; visual identification is not definitive.