mineral

Carnelian

Carnelian (Silicon Dioxide: SiO2)

Hardness: 6.5–7 (Mohs); Color: Pale orange to deep reddish-brown; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64

Hardness: 6
Color: Pale orange to deep reddish-brown
Luster: Waxy to vitreous

Identified March 25, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a cryptocrystalline variety of quartz (chalcedony) when silica-rich groundwater fills cavities in volcanic or sedimentary rocks. The red-orange tint comes from iron oxide impurities. It occurs in deposits of various geological ages from the Cretaceous to the present.

Uses & applications

Used primarily in jewelry-making (beads, cabochons), carvings, and historical seal stones. It is also a popular collector's mineral and used in metaphysical practices.

Geological facts

Ancient Romans used carnelian for signet rings because hot wax does not stick to it. It was also one of the first gemstones used in Egypt, dating back to 3000 BC, often associated with the goddess Isis.

Field identification & locations

Identify in the field by its waxy luster, translucency when held to light, and lack of visible crystal faces. Commonly found in riverbeds or gravel deposits in locations like Brazil, India, Madagascar, and the western USA.