gemstone

Tumbled carnelian

Chalcedony (microcrystalline quartz), SiO₂, colored by iron oxides

AI-generated identification · may be incorrect

Orange-red to brown, translucent, waxy to vitreous luster, no visible crystals, and hardness about 6.5–7 Mohs; conchoidal fracture and poor cleavage. The rounded, glossy form indicates tumbling and polishing.

Identified August 23, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or fractures, with iron producing the warm color; later weathering and tumbling shape the specimen. Chalcedony deposits range from relatively young volcanic-hosted material to Precambrian occurrences.

Uses & applications

Used for beads, cabochons, seals, carvings, and inexpensive jewelry; also collected as a lapidary stone.

Geological facts

Carnelian is the orange-red variety of chalcedony, grading into sard when darker brown-red. Heating can intensify or alter its color.

Field identification & locations

Commonly found in volcanic rocks, river gravels, and alluvial deposits, especially in India, Brazil, Uruguay, Madagascar, and Germany. Identify it by its uniform waxy translucence, hardness, and lack of cleavage; dyed glass may show bubbles or unnaturally even color.