gemstone

Tumbled carnelian or orange chalcedony

Chalcedony (microcrystalline quartz), SiO₂; likely iron-stained variety

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent cream, orange, and reddish-brown coloration with a waxy to vitreous luster. It has cryptocrystalline quartz structure, no visible cleavage, conchoidal fracture, and specific gravity around 2.6.

Identified August 19, 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 orange-red tones; commonly Cenozoic to older, depending on host rock.

Uses & applications

Used for beads, cabochons, carvings, and inexpensive ornamental objects; polished pieces are popular lapidary material.

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 by its smooth tumbled shape, waxy translucency, hardness, and lack of cleavage; it commonly occurs in volcanic geodes and alluvial gravels in India, Brazil, Uruguay, Madagascar, and the United States.