mineral

Carnelian

Silicon Dioxide (SiO2) - variety of Chalcedony

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs); Color: Orange, red, brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Hardness: 6
Color: Orange, red, brownish-red
Luster: Vitreous to waxy

Identified March 15, 2026More mineral →

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Physical properties

Hardness: 6.5-7 (Mohs); Color: Orange, red, brownish-red; Luster: Vitreous to waxy; Crystal Structure: Trigonal/Hexagonal (microcrystalline); Cleavage: None; Specific Gravity: 2.58-2.64

Formation & geological history

Forms as a precipitate in igneous or sedimentary cavities (vugs) at relatively low temperatures. The red coloring comes from iron oxide (hematite) impurities integrated during or after formation. Found in geological formations ranging from the Cretaceous to the modern day.

Uses & applications

Primary use is in jewelry, lapidary carvings (such as cameos), and decorative gemstones. Historically used for signet rings and wax seals because hot wax does not stick to it.

Geological facts

Ancient Egyptians referred to it as the 'Setting Sun' and associated it with the goddess Isis. It was one of the twelve stones mentioned in the Breastplate of Aaron in biblical texts and was famously worn by Napoleon Bonaparte as a seal.

Field identification & locations

Identify by its translucent quality, lack of visible crystals, and waxy luster. Frequently found in riverbeds or coastal gravels where volcanic activity once occurred. Common locations include Brazil, India, Uruguay, Madagascar, and the US (Oregon/Washington).