gemstone

Polished carnelian

Cryptocrystalline chalcedony (SiO₂), orange-red variety colored mainly by iron oxides

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent orange to reddish-brown, with a vitreous to waxy luster and no visible crystal grains. It is commonly tumbled or cabochon-polished and has conchoidal fracture rather than cleavage; specific gravity is about 2.58–2.64.

Identified August 23, 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 staining producing the orange color; deposits range from ancient volcanic terrains to younger sedimentary settings. Common sources include India, Brazil, Uruguay, Madagascar, Botswana, and the United States.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; historically valued as a durable engraved gemstone. Common polished pieces generally have modest commercial value.

Geological facts

Carnelian is a variety of chalcedony, itself a microcrystalline form of quartz; color may deepen with heat treatment. It can resemble orange glass or dyed agate.

Field identification & locations

Identify it by its even waxy translucence, lack of bubbles, hardness, and typically diffuse color bands or iron-rich patches; a quartz crystal will not scratch it, though glass may be scratched by it. The pictured rounded, polished orange specimen is consistent with carnelian, though exact identification requires testing.