gemstone

Tumbled carnelian/chalcedony

Cryptocrystalline quartz (SiO₂), likely iron-stained chalcedony

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent cream, peach, and orange-brown coloration with a smooth tumbled surface and waxy to weakly vitreous luster. It has no visible cleavage, a microcrystalline quartz structure, and specific gravity about 2.58–2.64.

Identified August 22, 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 hues; deposits range from volcanic rocks of many ages. The rounded shape indicates human tumbling and polishing.

Uses & applications

Used for cabochons, beads, carvings, and inexpensive jewelry; also collected as a decorative stone. Typical value is modest unless color and translucency are exceptional.

Geological facts

Carnelian is the orange-red variety of chalcedony, while paler material may be called orange chalcedony or sard. Color can be enhanced by heating or dyeing.

Field identification & locations

Identify it by its waxy translucency, quartz hardness, lack of cleavage, and conchoidal fracture; it should scratch glass but not be scratched by a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.