mineral

Carnelian Agate

Carnelian (Silicon Dioxide - SiO2)

Hardness: 6.5-7.0 (Mohs scale); Color: Reddish-orange to brownish-red; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal) microcrystalline; Cleavage: None (conchoidal fracture); Specific gravity: 2.58-2.64.

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

Identified April 13, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in the cavities of igneous rocks (basalts and rhyolites). The reddish color is due to the presence of iron oxide impurities (hematite).

Uses & applications

Predominantly used in jewelry, lapidary arts, bead-making, and as a semi-precious collector's stone. Historically used for signet rings and wax seals.

Geological facts

Ancient Egyptians referred to Carnelian as 'the setting sun' or 'the sunset stone'. It was widely used in the ancient world, particularly by Romans and Greeks, because hot wax does not stick to it, making it ideal for seals.

Field identification & locations

Identify by its translucent reddish-orange color and waxy luster. In the field, look for volcanic nodules or river-worn pebbles with a characteristic waxy translucent surface when chipped. Common locations include Brazil, India, Madagascar, and Uruguay.