mineral

Carnelian

SiO2 (Silicon Dioxide) - Carnelian Agate/Chalcedony

Hardness: 6.5-7 on Mohs scale; Color: reddish-orange to brownish-red; Luster: waxy to vitreous; Crystal structure: hexagonal (trigonal) cryptocrystalline; Cleavage: none; Specific gravity: 2.58-2.64.

Hardness: 6
Color: reddish-orange to brownish-red
Luster: waxy to vitreous

Identified February 26, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: reddish-orange to brownish-red; Luster: waxy to vitreous; Crystal structure: hexagonal (trigonal) cryptocrystalline; Cleavage: none; Specific gravity: 2.58-2.64.

Formation & geological history

Formed by the precipitation of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. The reddish hue is caused by iron oxide (hematite) impurities.

Uses & applications

Primarily used in jewelry for cabochons and beads, as well as for decorative carvings, seals, and historical talismans.

Geological facts

Carnelian was widely used in ancient Rome and Egypt for signet rings and amulets because it does not stick to hot wax. Napoleon Bonaparte notably found a carnelian seal in Egypt that he wore throughout his life.

Field identification & locations

Identify by its translucent reddish-orange color and waxy appearance; it lacks the banding seen in standard Agate. Commonly found in Brazil, India, Uruguay, and Madagascar. Use a scratch test with steel (it should not scratch) to verify hardness.

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