mineral

Carnelian

Carnelian (Microcrystalline Quartz, SiO2 with Fe2O3 impurities)

Hardness: 6.5-7 (Mohs scale); Color: Orange, red-orange, reddish-brown; Luster: Vitreous to waxy; Crystal structure: Trigonal/Hexagonal (microcrystalline/cryptocrystalline); Cleavage: None; Specific Gravity: 2.59-2.61.

Hardness: 6
Color: Orange, red-orange, reddish-brown
Luster: Vitreous to waxy

Identified March 25, 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, particularly volcanic lavas. The reddish hue is caused by iron oxide impurities. It occurs across various geological eras, notably appearing in alluvial deposits.

Uses & applications

Primarily used in jewelry (beads, cabochons), lapidary art, and engraving (seal stones). Historically significant for intaglios and cameos.

Geological facts

Ancient Romans used carnelian for signet rings because hot wax does not stick to the stone. It was also found in ancient Egyptian tombs, where it was believed to assist the soul's journey into the afterlife.

Field identification & locations

Identify by its translucent, waxy appearance and orange-red hue with no visible crystal grains. Often found as pebbles in riverbeds or within basaltic host rocks. Common locations include India, Brazil, Uruguay, and Madagascar.

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