gemstone

Polished orange chalcedony or carnelian

Microcrystalline quartz (SiO₂), commonly called carnelian when orange-red

AI-generated identification · may be incorrect

Small tumbled, translucent orange specimen with a waxy-to-glassy luster and no visible crystal faces. Quartz hardness is about 7 Mohs; specific gravity is approximately 2.60–2.65, with conchoidal fracture rather than cleavage.

Identified September 21, 2026More gemstone →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures, precipitating microcrystalline quartz; orange color usually comes from finely dispersed iron oxides. Chalcedony is common in volcanic rocks, especially basalt, and is geologically much younger than the host rock.

Uses & applications

Used for inexpensive cabochons, beads, carvings, ornaments, and rock collections. This appears to be a common tumbled piece rather than a high-grade faceted gemstone.

Geological facts

Carnelian is an orange variety of chalcedony; color can be natural or enhanced by heating. The photograph cannot reliably distinguish carnelian from orange jasper or dyed chalcedony.

Field identification & locations

Likely identification requires a hardness test: it should scratch ordinary glass, while a steel blade should not scratch it easily. Around 27.3°S, 52.3°W in southern Brazil, volcanic basalt and associated agate/chalcedony are regionally plausible; inspect for banding, iron-red zones, and uniform dye concentration.