gemstone

Polished carnelian (orange chalcedony)

Carnelian, a cryptocrystalline variety of quartz (SiO₂), colored mainly by iron oxides

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange to reddish-brown with cloudy bands and dark iron-rich patches; waxy to vitreous luster, no visible crystals, and conchoidal fracture. The smooth oval shape indicates a polished or cabochon-cut specimen.

Identified September 15, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron staining producing the orange-red color; deposits commonly range from Cenozoic to older volcanic-hosted settings. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.

Uses & applications

Used for cabochons, beads, carvings, seals, and ornamental objects; durable enough for everyday jewelry. Commercial value is generally modest unless color and translucency are exceptional.

Geological facts

Carnelian is closely related to sard and agate; boundaries are based largely on color and translucency. Heating can intensify its red-orange coloration, and some material sold as carnelian is heat-treated.

Field identification & locations

Identify it by its orange translucency, smooth waxy appearance, quartz-like hardness, and lack of cleavage; it should resist scratching by a steel knife. Typical specimens sell for about $5–$30; fine, strongly translucent cabochons may reach $50–$150.