mineral

Carnelian (Red Chalcedony)

Silicon Dioxide (SiO2)

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

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

Identified April 27, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed in volcanic and sedimentary rocks when silica-rich fluids permeate cavities. The red color is caused by impurities of iron oxide (hematite). Many specimens are found in basalt vugs.

Uses & applications

Predominantly used for jewelry, lapidary arts, decorative carvings, and as a collector's gemstone. Historically used for signet rings and cylinder seals.

Geological facts

Carnelian was highly prized in ancient Egypt, where it was believed to assist the soul in its journey to the afterlife. It was also one of the gems in the Breastplate of Aaron.

Field identification & locations

Identify by its translucent waxy luster and reddish hue. In the field, it is often found as smooth water-worn pebbles in riverbeds or within weathering volcanic flows. Common in Brazil, India, and Madagascar.