gemstone

Polished carnelian

Carnelian, orange-red chalcedony (microcrystalline quartz, SiO₂)

AI-generated identification · may be incorrect

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

Identified August 30, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich fluids fill cavities and fractures, with iron impurities producing the orange-red color; most deposits are Cenozoic to older sedimentary or volcanic-hosted occurrences. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable enough for everyday jewelry. Common polished pieces generally have modest value.

Geological facts

Carnelian is a variety of chalcedony and grades into sard, which is darker brown-red. Ancient Egyptians, Greeks, Romans, and Mesopotamians used it extensively for amulets and engraved gems.

Field identification & locations

Identify it by its even orange-red body color, translucency, waxy polish, hardness, and absence of cleavage; glass may show bubbles or stronger transparency. Natural color can be tested cautiously with a loupe, though dyeing and heat treatment are common.