gemstone

Tumbled carnelian (orange chalcedony)

Carnelian, a microcrystalline variety of quartz (SiO₂)

AI-generated identification · may be incorrect

Translucent orange to reddish-brown, waxy-to-glassy luster, typically cryptocrystalline with no visible cleavage; Mohs hardness 6.5–7 and specific gravity about 2.60–2.65. The smooth rounded shape indicates tumbling or water wear.

Identified August 27, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; iron impurities create the orange-red color. Deposits occur from the Cenozoic to older geological ages, depending on locality.

Uses & applications

Used for beads, cabochons, carvings, ornaments, and inexpensive jewelry; historically used for seals and amulets.

Geological facts

Carnelian is closely related to sard and agate, differing mainly in color and banding. Heating can intensify its red-orange coloration.

Field identification & locations

Identify by its orange-red translucent body, waxy surface, lack of cleavage, and hardness sufficient to scratch glass. Common sources include India, Brazil, Uruguay, Madagascar, and the United States; dyes and coatings are possible in commercial pieces.