Rock Identifier
Carnelian (Chalcedony (Silicon Dioxide, SiO2 with Iron Oxide impurities)) — mineral
mineral

Carnelian

Chalcedony (Silicon Dioxide, SiO2 with Iron Oxide impurities)

Hardness: 6.5-7 (Mohs). Color: Translucent reddish-orange to brownish-red. Luster: Vitreous to waxy. Crystal structure: Trigonal/Microcrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.58-2.64.

Hardness
6
Color
Translucent reddish-orange to brownish-red
Luster
Vitreous to waxy
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Physical properties

Hardness: 6.5-7 (Mohs). Color: Translucent reddish-orange to brownish-red. Luster: Vitreous to waxy. Crystal structure: Trigonal/Microcrystalline. Cleavage: None (conchoidal fracture). Specific gravity: 2.58-2.64.

Formation & geological history

Formed through the percolation of silica-rich groundwater into cavities or veins within volcanic or sedimentary rocks. The red tint is caused by iron oxide (hematite) inclusions. It can be found in formations ranging from the Precambrian to recent alluvial deposits.

Uses & applications

Used primarily in jewelry making for beads, cabochons, and intaglios. Historically used for seal stones and signet rings because hot wax does not stick to it.

Geological facts

Carnelian was highly prized in Ancient Egypt where it was believed to represent the sunset and was frequently found in the tombs of Pharaohs. It is one of the oldest semi-precious gemstones recorded in history, dating back to 4500 BC.

Field identification & locations

Identify in the field by its uniform orange-red translucent color and smooth, glass-like fracture. Common locations include Brazil, India, Madagascar, and Uruguay. It is a popular 'entry-level' gemstone for many collectors due to its vibrant color and affordability.

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