mineral

Tumbled brown chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; opaque to slightly translucent brown with gray areas, waxy to dull luster, and no visible cleavage. The smooth rounded form indicates mechanical tumbling and polishing.

Identified September 7, 2026More mineral →

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Physical properties

Hardness 6.5–7 Mohs; opaque to slightly translucent brown with gray areas, waxy to dull luster, and no visible cleavage. The smooth rounded form indicates mechanical tumbling and polishing.

Formation & geological history

Silica-rich groundwater deposited microcrystalline quartz in cavities or fractures, with iron oxides producing the brown coloration; the precise geological age and source cannot be determined from the image.

Uses & applications

Used as a lapidary stone for cabochons, carvings, jewelry, and decorative tumbled stones; typically modestly priced.

Geological facts

Jasper is opaque and commonly patterned, while chalcedony is more translucent; this specimen may be an iron-rich mixture of both, often marketed generically as brown jasper.

Field identification & locations

Common in volcanic and sedimentary environments worldwide, especially India, Brazil, Madagascar, Uruguay, and the western United States. Field clues include waxy luster, conchoidal fracture, lack of cleavage, and failure to scratch it with a steel knife.