mineral

Carnelian (Red Chalcedony)

SiO2 (Silicon Dioxide with Hematite impurities)

Hardness: 6.5-7 on Mohs scale. Color: reddish-orange to brownish-red. Luster: vitreous to waxy. Crystal structure: trigonal (microcrystalline/cryptocrystalline quartz). Cleavage: none, shows conchoidal fracture.

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

Identified July 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms at low temperatures through the deposition of silica-rich solutions within cavity voids, fractures, and vesicles in volcanic rocks and sedimentary environments. Impurities of iron oxide give it its distinctive warm reddish color.

Uses & applications

Popular gemstone for jewelry (beads, cabochons, carved intaglios), decorative carvings, polished display stones, and lapidary art. Historically used for seals and signet rings.

Geological facts

Carnelian has been used by humans for over 4,500 years. Ancient Egyptians called it the 'setting sun' and crafted it into protective amulets. Roman officers used carnelian signet rings to seal important wax documents because hot wax does not stick to it.

Field identification & locations

Identified by its translucent to semi-translucent warm orange-red color, smooth waxy surface texture, and conchoidal fracture. Commonly found in Brazil, India, Madagascar, Uruguay, and the northwestern USA.

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