mineral

Tumbled carnelian (red chalcedony)

Carnelian, a microcrystalline variety of quartz (SiO₂)

AI-generated identification · may be incorrect

Typically translucent reddish-brown to orange, with waxy-to-glassy luster and no visible crystals; Mohs hardness 6.5–7, conchoidal fracture, and specific gravity about 2.6. The rounded, glossy surface indicates tumbling or polishing.

Identified August 19, 2026More mineral →

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Physical properties

Formation & geological history

Forms when iron-bearing silica-rich groundwater fills cavities and fractures, later acquiring red color through iron-oxide inclusions and heat exposure. Chalcedony deposits range from ancient volcanic rocks to younger sedimentary gravels.

Uses & applications

Used for beads, cabochons, carvings, ornamental objects, and inexpensive jewelry; polished pieces are popular lapidary and metaphysical collectibles.

Geological facts

Carnelian is a variety of chalcedony closely related to agate; color may deepen with gentle heating. It was widely used for seals and jewelry in ancient Egypt, Rome, and Mesopotamia.

Field identification & locations

Identify it by its uniform reddish-brown color, translucency at thin edges, hardness, and lack of cleavage; glass may show bubbles, while dyed material can have concentrated color in cracks. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.