mineral

Carnelian (Agate / Chalcedony)

Silicon Dioxide (SiO2) - Iron-stained Chalcedony

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange, honey-yellow, to brownish-red; Luster: Waxy to vitreous; Crystal Structure: Microcrystalline Trigonal/Hexagonal; Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64

Hardness: 6
Color: Reddish-orange, honey-yellow, to brownish-red
Luster: Waxy to vitreous

Identified July 24, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids deposit in cavities and fractures within volcanic or sedimentary rocks. The reddish-orange color is caused by traces of iron oxide (hematite or goethite) impurities within the cryptocrystalline quartz matrix.

Uses & applications

Widely used for gemstones, jewelry beads, cabochons, carvings, seal rings, decorative tumbled stones, and holistic crystal practices.

Geological facts

Carnelian has been used for over 4,500 years; ancient Romans and Egyptians used it to make signet rings for sealing wax because hot wax does not stick to carnelian.

Field identification & locations

Identified by its translucent orange-red color, waxy luster, smooth conchoidal fracture surface, and inability to be scratched by a steel blade. Commonly found in Brazil, India, Madagascar, Uruguay, and the USA (Oregon, Washington).

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