mineral

Orange chalcedony (possibly carnelian)

Microcrystalline quartz, SiO₂; iron-oxide-bearing chalcedony

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, waxy to dull luster, translucent orange-brown color, and no visible cleavage; it has a cryptocrystalline quartz structure and specific gravity near 2.60. The mottled bands and rusty inclusions suggest iron staining or brecciation.

Identified August 28, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron oxides producing orange to red coloration; deposits range from volcanic-hosted cavities to sedimentary siliceous veins, commonly Cenozoic to older. The exact age and locality cannot be determined from the photograph.

Uses & applications

Used as ornamental stone, cabochons, beads, carvings, and lapidary material; small rough pieces generally have modest collecting value.

Geological facts

Carnelian is the reddish-orange variety of chalcedony, while paler orange material is often called orange chalcedony. Color may intensify with heat treatment, and iron-rich areas can weather brown or yellow.

Field identification & locations

Common sources include India, Brazil, Uruguay, Madagascar, Namibia, and the United States. Identify it by its hardness, waxy appearance, translucent edges, and lack of cleavage; it should scratch glass but not be scratched by a steel knife.