gemstone

Tumbled carnelian (red-orange chalcedony)

Carnelian, cryptocrystalline quartz (SiO₂), a variety of chalcedony

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent orange, reddish-brown color with waxy to vitreous luster. Microcrystalline quartz has no visible cleavage and conchoidal fracture; typical specific gravity is about 2.6.

Identified August 28, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron oxides producing the red-orange color; commonly associated with volcanic rocks and ancient river gravels. Deposits range from Precambrian to recent in age.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; polished pieces are popular inexpensive gemstones and collector specimens.

Geological facts

Color may be enhanced by gentle heating, which deepens iron-oxide reds. Carnelian was widely used for seals and jewelry in ancient Egypt, Greece, Rome, and Mesopotamia.

Field identification & locations

Identify by its orange-red translucent body color, waxy polish, hardness, and conchoidal fracture; it should not scratch easily with a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.