gemstone

Tumbled carnelian/chalcedony

Microcrystalline quartz (SiO₂), likely iron-colored chalcedony

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange, peach, and reddish-brown zones with a waxy to vitreous luster. Trigonal quartz structure, cryptocrystalline texture, and no visible cleavage; specific gravity is about 2.58–2.64.

Identified August 13, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron oxides producing the orange-red color; deposits commonly range from volcanic-hosted Cenozoic to older sedimentary environments. The rounded shape indicates human tumbling and polishing.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and lapidary collections; historically used for seals and amulets. Common polished pieces have modest commercial value.

Geological facts

Carnelian is the orange-red variety of chalcedony, while paler orange material may be called sard or orange chalcedony. Color can be enhanced by heating or dyeing, though this specimen appears naturally patterned or mildly treated.

Field identification & locations

Identify it by its translucency, smooth waxy surface, quartz-level hardness, and resistance to scratching by steel; glass should not scratch it. Common sources include India, Brazil, Uruguay, Madagascar, and Namibia.