mineral

Carnelian Agate

Carnelian (Silicon Dioxide: SiO2) with iron oxide impurities

Hardness: 6.5-7 on Mohs scale; Color: Translucent orange, red, or brownish-red; Luster: Vitreous to waxy; Crystal Structure: Hexagonal (trigonal) microcrystalline/cryptocrystalline; Cleavage: None; Specific Gravity: 2.58–2.64

Hardness: 6
Color: Translucent orange, red, or brownish-red
Luster: Vitreous to waxy

Identified March 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater within the cavities of igneous (volcanic) rocks or sedimentary formations. The distinct orange color is caused by the presence of hematite or iron oxide. It can be found in formations ranging from the Cretaceous period to more recent geological eras.

Uses & applications

Primarily used in jewelry (beads, cabochons, carved intaglios), decorative carvings, and as a collector's specimen. In antiquity, it was widely used for seal stones and amulets.

Geological facts

Carnelian was highly valued in ancient Egypt, where it was believed to represent the sunset; it was found in the burial chambers of Tutankhamun. It is often heat-treated to enhance its reddish hue.

Field identification & locations

Identify in the field by its waxy luster, conchoidal fracture, and lack of visible crystals. It is commonly found in Brazil, India, Uruguay, Madagascar, and the United States (Washington, Oregon). Look for smooth, translucent orange-red nodules in gravel beds or volcanic regions.

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