gemstone

Tumbled carnelian (red-orange chalcedony)

Carnelian, a microcrystalline variety of quartz (SiO₂), colored mainly by iron oxides

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent reddish-orange to brown, with vitreous-to-waxy luster and no visible cleavage. It has a cryptocrystalline trigonal quartz structure and typically shows smooth, conchoidal fracture; the pictured piece is polished/tumbled.

Identified August 26, 2026More gemstone →

Explore Tumbled carnelian (red-orange chalcedony) 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 fluids fill cavities and fractures, later acquiring red coloration from iron oxides or hydroxides; commonly associated with volcanic rocks and ancient volcanic sedimentary deposits. Individual pieces may range from relatively young to Precambrian in source age.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive jewelry; historically valued as a seal stone and amulet.

Geological facts

Carnelian is a variety of chalcedony, closely related to sard; heating can intensify its orange-red color. It may be confused with dyed agate, glass, or red jasper.

Field identification & locations

Identify by its warm translucent color, fine-grained texture, hardness, and absence of cleavage; common sources include India, Brazil, Uruguay, Madagascar, and Germany. Natural color is often uneven, while dyed material may show concentrated color in cracks.