mineral

Carnelian Agate

Silicon Dioxide (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange to brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal) microcrystalline; Cleavage: None; Specific gravity: 2.58-2.64

Hardness: 6
Color: Reddish-orange to brown
Luster: Vitreous to waxy

Identified May 18, 2026More mineral →

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Physical properties

Hardness: 6.5-7 on Mohs scale; Color: Reddish-orange to brown; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal) microcrystalline; Cleavage: None; Specific gravity: 2.58-2.64

Formation & geological history

Formed in volcanic and sedimentary rocks as silica-rich groundwater percolates through cavities, depositing layers of chalcedony over time. Distinctive coloring comes from iron oxide impurities.

Uses & applications

Used primarily in jewelry (cabochons and beads), decorative carvings, and as a collector's specimen.

Geological facts

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

Field identification & locations

Identify by its translucent reddish-orange hue and waxy luster. Commonly found in Brazil, India, Uruguay, and Madagascar. Collectors look for uniform color and high translucency.