gemstone

Polished red-orange chalcedony (likely carnelian)

Carnelian, a microcrystalline variety of quartz; SiO₂, commonly colored by iron oxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent orange-red to reddish brown with a waxy-to-glassy luster and no visible crystal faces. It has cryptocrystalline quartz structure, conchoidal fracture, and no cleavage; the surface appears polished or coated, with possible natural pits/inclusions.

Identified September 17, 2026More gemstone →

Explore Polished red-orange chalcedony (likely carnelian) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later acquiring its color from oxidized iron. Deposits occur in volcanic rocks and sediments, generally from Phanerozoic environments rather than a single geological age.

Uses & applications

Used for cabochons, beads, carvings, seals, and ornamental objects; also collected as a relatively common quartz gemstone.

Geological facts

Carnelian is often heat-treated or dyed to intensify red-orange color, and ordinary chalcedony can be difficult to distinguish visually without testing.

Field identification & locations

Common localities include India, Brazil, Uruguay, Madagascar, Germany, and the western United States. Field clues are its waxy translucency, conchoidal fracture, lack of cleavage, and ability to scratch glass; acid testing is not diagnostic.