gemstone

Tumbled carnelian (orange chalcedony)

Carnelian, a microcrystalline variety of quartz; SiO₂, commonly colored by iron oxides

AI-generated identification · may be incorrect

Typically orange to reddish-brown, translucent, waxy to vitreous luster, hardness 6.5–7 Mohs, cryptocrystalline structure, no visible cleavage, and specific gravity about 2.6. The rounded, glossy surface indicates tumbling and polishing.

Identified August 28, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or fractures in volcanic rocks, with iron impurities producing the orange color; many deposits are Cenozoic to older. Heating can intensify its red-orange color.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable enough for jewelry but less valuable than fine transparent gemstones.

Geological facts

Carnelian is closely related to sard and agate, differing mainly in color and translucency. Ancient Egyptians, Greeks, Romans, and Islamic cultures used it extensively for amulets and engraved seals.

Field identification & locations

Identify by its uniform orange color, translucency, waxy luster, and lack of cleavage; glass imitations may contain bubbles and feel less natural. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.