gemstone

Polished carnelian/chalcedony

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; orange, honey-yellow, cream, and reddish-brown coloration; waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture. The rounded, glossy surface indicates tumbling or polishing.

Identified September 17, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, with iron oxides producing the red-orange colors. Chalcedony deposits are commonly Cenozoic to older, depending on the host rock.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive jewelry; polished pieces are popular collecting specimens.

Geological facts

Carnelian is the orange-red variety of chalcedony, while paler honey material may be called sard or ordinary chalcedony. Color can intensify through heating or dyeing.

Field identification & locations

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