gemstone

Tumbled carnelian/chalcedony

Cryptocrystalline quartz (SiO₂), likely iron-stained chalcedony

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent cream, orange, and reddish-brown bands or patches; waxy to vitreous luster; trigonal quartz structure with no cleavage and conchoidal fracture. The rounded shape indicates tumbling and polishing.

Identified September 15, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and veins, with iron oxides producing the red-orange coloration; commonly Cenozoic to older volcanic-hosted material. Exact age and locality cannot be determined from the photograph.

Uses & applications

Used for cabochons, beads, carvings, and inexpensive jewelry; also collected as an attractive tumbled stone. Typical value is about $2–$15 for a small polished piece, or $20–$75 for unusually vivid, patterned material.

Geological facts

Carnelian is the red-orange variety of chalcedony; color may deepen with gentle heating. It is closely related to agate, but agate typically shows more distinct banding.

Field identification & locations

Identify it by its glassy/waxy polish, translucency, warm iron-rich colors, and inability to scratch with a steel knife; it should scratch glass. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.