gemstone

Orange chalcedony or carnelian

Microcrystalline quartz, SiO₂ (chalcedony variety; iron-colored carnelian)

AI-generated identification · may be incorrect

Small translucent orange-yellow fragment with a waxy to vitreous luster and irregular fracture; likely Mohs hardness 6.5–7, no obvious cleavage, and specific gravity near 2.6. The pale internal streaks may be fractures, banding, or surface reflections.

Identified September 21, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, with iron oxides producing orange-red coloration. Chalcedony is common in volcanic rocks, including the basaltic terrains of southern Brazil, generally formed from Cenozoic to older hydrothermal weathering processes.

Uses & applications

Used for cabochons, beads, carvings, and ornamental stone; attractive pieces have modest jewelry value. Small rough fragments are mainly collector specimens.

Geological facts

Carnelian is the red-orange end of the chalcedony color range; yellow-orange material may be called orange chalcedony or sard. Color can be enhanced by heating or dyeing, though this specimen cannot be confirmed as untreated from the image.

Field identification & locations

Likely identification requires a hardness test: it should scratch ordinary glass but not be scratched by a steel knife. Quartz-like translucency and absence of cleavage support chalcedony; inspect for conchoidal fracture and test streak, avoiding damage to valuable material.