gemstone

Carnelian

Carnelian, orange-red cryptocrystalline quartz (SiO₂), a chalcedony variety

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange to reddish-brown, waxy to vitreous luster, fibrous microcrystalline structure, and no visible cleavage. The rounded, glossy surface indicates a tumbled or polished specimen.

Identified September 15, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron impurities producing the orange-red color; deposits are commonly Cenozoic to older. It occurs in volcanic rocks, sedimentary gravels, and hydrothermal veins.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable enough for everyday jewelry. Common commercial material is affordable, while vivid, evenly colored pieces command premiums.

Geological facts

Carnelian is a red-orange chalcedony closely related to sard; heating can intensify or alter its color. Ancient Egyptians and Romans used it extensively for seals and amulets.

Field identification & locations

Identify it by its translucent orange-red body, waxy luster, lack of cleavage, and quartz hardness; it should scratch glass but not be scratched by a steel blade. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.