gemstone

Tumbled orange chalcedony (probable carnelian)

Microcrystalline quartz, SiO₂; iron-bearing orange chalcedony

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, waxy to vitreous luster, translucent orange to reddish-brown color, cryptocrystalline structure, and no visible cleavage; density is about 2.6 g/cm³. The rounded, polished shape indicates human tumbling or cutting.

Identified September 8, 2026More gemstone →

Explore Tumbled orange chalcedony (probable carnelian) in the encyclopedia →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rocks, with iron oxides producing the orange-red color. Deposits range from relatively young volcanic terrains to ancient Paleozoic and older sedimentary-hosted occurrences.

Uses & applications

Used for cabochons, beads, carvings, ornamental objects, and inexpensive jewelry; attractive banded or strongly saturated pieces are collectible.

Geological facts

Carnelian is the orange-red variety of chalcedony and is closely related to agate. Color may be naturally enhanced or heat-treated to intensify red-orange tones.

Field identification & locations

Identify by its hardness, smooth waxy appearance, translucency, and lack of cleavage; it should resist scratching by a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and the United States.