gemstone

Carnelian (red chalcedony)

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

AI-generated identification · may be incorrect

Typically orange-red to reddish brown, translucent at thin edges, with a waxy to vitreous luster and conchoidal fracture; Mohs hardness 6.5–7, no cleavage, cryptocrystalline structure, and specific gravity about 2.60–2.65.

Identified August 10, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later acquiring red coloration from dispersed iron oxides. It commonly occurs in volcanic rocks and sedimentary gravels, generally formed during relatively recent geological episodes rather than one specific age.

Uses & applications

Used for cabochons, beads, carvings, seals, and ornamental objects; attractive lapidary-grade pieces have modest jewelry value.

Geological facts

Carnelian is a variety of chalcedony; banding may be absent or subtle. Heating can intensify its red-orange color, and dyed look-alikes are common.

Field identification & locations

Identify it by its glassy/waxy appearance, translucency, conchoidal break, lack of cleavage, and inability to scratch it with a steel nail easily; common sources include India, Brazil, Uruguay, Madagascar, and the United States.