gemstone

Tumbled carnelian (red-orange chalcedony)

Microcrystalline quartz, SiO₂; chalcedony colored mainly by iron oxides

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, orange-red to brown-red, translucent to opaque, with a waxy or vitreous luster and no visible cleavage. The rounded, glossy surface indicates mechanical tumbling and polishing; blue highlights are likely reflected light or surface coating rather than natural color.

Identified September 6, 2026More gemstone →

Explore Tumbled carnelian (red-orange chalcedony) in the encyclopedia →

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Physical properties

Formation & geological history

Forms when silica-rich fluids fill cavities and fractures, depositing cryptocrystalline quartz; iron impurities create the red coloration. Deposits occur in volcanic rocks and sedimentary gravels, commonly ranging from Cenozoic to older ages.

Uses & applications

Used for beads, cabochons, carvings, decorative stones, and inexpensive jewelry; polished pieces are popular collectibles.

Geological facts

Carnelian is a variety of chalcedony closely related to sard; ancient Egyptians, Greeks, and Romans used it for seals, amulets, and jewelry.

Field identification & locations

Identify by its uniform red-orange color, fine texture, lack of cleavage, hardness, and waxy polish; it should not show distinct quartz crystals. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.