mineral

Tumbled carnelian/chalcedony

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, waxy to vitreous luster, translucent orange-brown color, and no visible cleavage; conchoidal fracture is characteristic. The specimen appears polished or naturally water-worn, with cream and reddish inclusions.

Identified August 8, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later becoming cryptocrystalline quartz; iron oxides produce the orange-red coloration. Chalcedony deposits commonly formed in volcanic rocks during the Cenozoic and older geological periods.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and lapidary pieces; durable varieties are also used for small tools and decorative stone. This appears to be a modest tumbled or rough jewelry specimen.

Geological facts

Carnelian is the orange-red variety of chalcedony, while paler brown-orange material may be called sard. Color can intensify after gentle heating because iron minerals oxidize.

Field identification & locations

Identify by its waxy luster, translucency, hardness, curved fracture, and lack of cleavage; it should scratch glass but not be scratched easily by a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and Namibia.