gemstone

Polished carnelian/chalcedony

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

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent reddish-orange to brown with a waxy-to-glassy luster and no visible cleavage. Its rounded, glossy surface indicates tumbling or polishing; color commonly comes from iron oxides.

Identified August 10, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later incorporating iron during alteration; commonly associated with volcanic rocks, especially basalt and rhyolite. Deposits range from Paleozoic to younger, with exact age undeterminable from the image.

Uses & applications

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

Geological facts

Carnelian is technically chalcedony, composed of intergrown quartz fibers too fine to see unaided. Heating or staining can intensify its red-orange color, so untreated status affects value.

Field identification & locations

Identify by its orange-red translucent body, waxy luster, conchoidal fracture, and quartz hardness; it should resist scratching by a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.