mineral

Red chalcedony (likely carnelian)

Chalcedony, microcrystalline quartz (SiO₂); red color commonly from iron oxides

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent to semi-opaque reddish red, with waxy to vitreous luster and conchoidal fracture. It lacks visible crystals and cleavage; specific gravity is about 2.58–2.64.

Identified August 27, 2026More mineral →

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Physical properties

Mohs hardness 6.5–7; translucent to semi-opaque reddish red, with waxy to vitreous luster and conchoidal fracture. It lacks visible crystals and cleavage; specific gravity is about 2.58–2.64.

Formation & geological history

Forms when silica-rich groundwater deposits microscopic quartz fibers in cavities and fractures, with iron producing the red coloration. It occurs in volcanic rocks and sedimentary nodules, generally from relatively young to ancient geological settings.

Uses & applications

Used for cabochons, beads, carvings, and decorative objects; durable pieces are popular in inexpensive to moderate-value jewelry.

Geological facts

Carnelian is the orange-red to red variety of chalcedony; darker red material is often called sard. Color may be naturally intensified or enhanced by heating.

Field identification & locations

Common localities include India, Brazil, Uruguay, Madagascar, Germany, and the western United States. Identify it by its waxy luster, translucency, conchoidal breaks, and lack of cleavage; quartz hardness distinguishes it from glass and calcite.