mineral

Carnelian (a variety of Chalcedony)

SiO2 (Silicon Dioxide with Iron Oxide impurities)

Hardness: 6.5-7 on Mohs scale; Color: brownish-red to orange-red; Luster: waxy to vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

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

Identified March 8, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: brownish-red to orange-red; Luster: waxy to vitreous; Crystal Structure: Trigonal (Microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks, particularly volcanic lavas. The reddish hue is caused by iron oxide impurities. Age varies widely depending on the host rock, often Cenozoic or Mesozoic.

Uses & applications

Primarily used in jewelry as cabochons, beads, and engravings (intaglios). Historically used for seal stones due to its property of not sticking to hot wax.

Geological facts

Ancient Egyptians called carnelian 'the setting sun' and buried their dead with it for protection. It was also one of the stones in the High Priest's Breastplate mentioned in the Bible.

Field identification & locations

Identify in the field by its translucent orange-red color, waxy luster, and conchoidal (shell-like) fracture. Found commonly in Brazil, India, Uruguay, and the United States (Washington/Oregon).

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