gemstone

Tumbled carnelian/chalcedony

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony or pale carnelian

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent cream to orange-brown with rusty red inclusions, waxy to vitreous luster, cryptocrystalline structure, and no visible cleavage. Specific gravity is about 2.58–2.64.

Identified September 15, 2026More gemstone →

Explore Tumbled carnelian/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 groundwater fills cavities and fractures, with iron oxides producing the orange-red staining; commonly Cenozoic to older volcanic or sedimentary host rocks. The rounded shape indicates human tumbling and polishing.

Uses & applications

Used for beads, cabochons, carvings, decorative stone, and inexpensive jewelry; quality is primarily determined by color, translucency, pattern, and polish.

Geological facts

Carnelian is the orange-red variety of chalcedony, while paler material may be called sard or iron-stained agate. Its color can deepen with heating or prolonged exposure to sunlight.

Field identification & locations

Identify it by its smooth waxy polish, lack of cleavage, translucency, and hardness sufficient to scratch glass; rusty patches suggest hematite/goethite staining. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.