mineral

Carnelian (Carnelian Agate)

Silicon dioxide (SiO2)

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

Hardness: 6
Color: Red-orange to reddish-brown
Luster: Vitreous to waxy

Identified June 9, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica-rich groundwater in cavities of igneous rocks, particularly volcanic basalts and andesites. The orange-red color is caused by impurities of iron oxide (hematite).

Uses & applications

Predominantly used as a gemstone in jewelry (cabochons, beads), for engravings and intaglio signet rings, and as a popular specimen for crystal collecting.

Geological facts

In ancient times, carnelian was believed to calm anger and ward off the evil eye. It was one of the first stones used in the Neolithic for bead making and was highly prized by Roman and Egyptian civilizations.

Field identification & locations

Identify by its translucent waxy luster and warm orange hue. It is commonly found in Brazil, India, Madagascar, and Uruguay. Field identification involves looking for chalcedony with a distinctive uniform or banded orange color and a conchoidal (shell-like) fracture.