gemstone

Tumbled carnelian (red-orange chalcedony)

Carnelian, a cryptocrystalline variety of quartz: SiO₂

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; translucent to opaque orange-red, with a waxy to vitreous luster and no visible crystals. It consists of fibrous microcrystalline quartz and commonly shows iron-oxide staining or banding.

Identified August 10, 2026More gemstone →

Explore Tumbled carnelian (red-orange chalcedony) in the encyclopedia →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, later acquiring its red color from iron oxides; deposits range from Paleozoic to Cenozoic in age. Common sources include India, Brazil, Uruguay, Madagascar, and Germany.

Uses & applications

Used for beads, cabochons, carvings, seals, and ornamental objects; durable enough for jewelry and decorative stonework.

Geological facts

Carnelian is a traditional gemstone associated with vitality and protection, and it was widely used in ancient Egyptian and Roman seals.

Field identification & locations

Identify it by its orange-to-red color, translucency, waxy polish, and hardness; it should resist scratching by a steel knife but be scratched by quartz. Natural color may be uneven or banded; vivid uniformly red pieces are sometimes heat-treated.