gemstone

Polished carnelian

Carnelian, a red-orange variety of chalcedony (microcrystalline quartz, SiO₂)

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent to opaque reddish-brown color, vitreous to waxy luster, cryptocrystalline quartz structure, and no visible cleavage. The smooth, rounded surface indicates tumbling or polishing.

Identified August 21, 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 color; commonly associated with volcanic rocks and Cenozoic to older sedimentary deposits.

Uses & applications

Used for beads, cabochons, carvings, ornamental objects, and inexpensive jewelry. It is also a popular lapidary and collecting material.

Geological facts

Carnelian’s color ranges from orange to deep red-brown; heating can intensify or alter the color. It may resemble red jasper, sard, or dyed agate.

Field identification & locations

Common sources include India, Brazil, Uruguay, Madagascar, and Germany. Field clues include hardness sufficient to scratch glass, waxy translucency, conchoidal fracture, and lack of distinct crystal faces; a polished specimen cannot be reliably identified from appearance alone.