gemstone

Carnelian (red-orange chalcedony)

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

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent reddish-orange to brown, with waxy/glassy luster and conchoidal fracture. It lacks visible cleavage and consists of interlocking microscopic quartz fibers; the rough outer surface may be a natural cortex or host-rock coating.

Identified August 28, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later stained by iron oxides; commonly associated with volcanic rocks. Deposits range from Precambrian to recent in age.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable and attractive but generally less valuable than fine agate or crystalline quartz.

Geological facts

Carnelian is a variety of chalcedony, with color intensity controlled largely by iron content and oxidation state. Heating can deepen its red-orange color.

Field identification & locations

Identify by its translucent warm color, waxy luster, lack of cleavage, and hardness sufficient to scratch window glass; it should not fizz in dilute acid. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.