gemstone

Tumbled carnelian/chalcedony

Orange chalcedony, microcrystalline quartz (SiO₂), likely iron-oxide-bearing

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent white, orange, and reddish-brown coloration with a waxy to vitreous luster. It has cryptocrystalline quartz structure, no visible cleavage, and conchoidal fracture; the smooth surface is tumbled and polished.

Identified September 15, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, later incorporating iron oxides that create orange-red colors. Chalcedony commonly formed in volcanic rocks during the Cenozoic and earlier geological periods.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and inexpensive jewelry; polished pieces are also popular mineral specimens.

Geological facts

The orange-red variety is commonly marketed as carnelian, though boundaries between carnelian and other orange chalcedony are informal. Stronger red color generally indicates more iron oxide and can be enhanced by heating.

Field identification & locations

Identify it by its smooth waxy appearance, translucency, hardness, and absence of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include India, Brazil, Uruguay, Madagascar, and Namibia.