mineral

Carnelian

Carnelian (Silicon Dioxide - SiO2)

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

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

Identified April 4, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in low-temperature hydrothermal environments where silica-rich fluids deposit in cavities of volcanic rocks. The red color is caused by impurities of iron oxide (hematite).

Uses & applications

Predominantly used for jewelry, lapidary arts, and ornamental carvings. Historically used for seals and signet rings because hot wax does not stick to it.

Geological facts

Carnelian was highly prized in ancient Egypt, where it was thought to provide protection and courage. It was used in many of the artifacts found in Tutankhamun's tomb.

Field identification & locations

Identify by its translucency and uniform reddish-orange color. It is common in India, Brazil, Uruguay, and Madagascar. In the field, look for volcanic host rocks and use a hardness test to distinguish from plastic or glass.