mineral

Tumbled chalcedony (likely carnelian or brown jasper)

Microcrystalline quartz, SiO₂; iron-bearing varieties may be called carnelian

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; orange-brown, waxy to vitreous luster, opaque to translucent, with no visible cleavage and a conchoidal fracture. The rounded, glossy surface indicates mechanical tumbling and polishing.

Identified August 26, 2026More mineral →

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Physical properties

Formation & geological history

Silica-rich groundwater fills cavities and fractures in volcanic rocks, forming chalcedony over geologic time; iron oxides create the warm brown-orange color. Exact age cannot be determined from the photograph.

Uses & applications

Used as a lapidary stone, bead, cabochon, ornament, and collector specimen; carnelian is also used in jewelry. Common tumbled pieces typically have modest commercial value.

Geological facts

Chalcedony is composed of microscopic quartz crystals and may grade visually into jasper when strongly opaque. Heating or dyeing can intensify orange-red coloration, so untreated and treated pieces may look similar.

Field identification & locations

Commonly found in volcanic terrains, especially Brazil, India, Madagascar, Uruguay, and the western United States. Field tests include glass-scratching hardness and a white streak; acid does not noticeably react.