mineral

Carnelian Agate

Silicon Dioxide (SiO2)

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

Hardness: 6
Color: Reddish-orange to brownish-red
Luster: Vitreous to waxy

Identified May 10, 2026More mineral →

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Physical properties

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

Formation & geological history

Forms in volcanic rocks (cavities in basalt or andesite) where silica-rich groundwater precipitates. It can be found in secondary alluvial deposits after the host rock erodes.

Uses & applications

Primarily used in jewelry (beads, cabochons, carved seals), decorative carvings, and as a popular collector stone.

Geological facts

Carnelian has been used for over 4,500 years; Ancient Romans used it for signet rings because hot wax does not stick to it.

Field identification & locations

Identify by its translucent reddish-orange hue and waxy luster. In the field, look for river-worn pebbles with a smooth, glass-like fracture and orange-red skin.