gemstone

Carnelian (red chalcedony)

Chalcedony, microcrystalline quartz (SiO₂), iron-oxide colored variety

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent reddish-orange to brown-red, with vitreous to waxy luster and no visible cleavage. It has a cryptocrystalline quartz structure and typically shows smooth conchoidal fractures; this specimen is polished/tumbled.

Identified August 9, 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 impurities producing the red color. Deposits range from ancient to recent and occur worldwide.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable enough for everyday jewelry. Common tumbled pieces generally have modest collector value.

Geological facts

Carnelian is a variety of chalcedony closely related to sard, which is typically darker and browner. Heating can intensify or alter its red-orange color.

Field identification & locations

Identify it by its even red-orange color, translucency, waxy polish, and lack of cleavage; glass may show bubbles and a more uniformly glassy luster. Common sources include India, Brazil, Uruguay, Madagascar, and Namibia.