Carnelian
Chalcedony var. Carnelian · Semi-Precious Gemstone
Crystal System
Trigonal (Hexagonal); Microcrystalline/Cryptocrystalline habit, typically massive or as rounded pebbles
Mineral Group
Silicates (Subgroup: Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide) with Iron Oxide (Fe2O3) inclusions
Formation Process
Hydrothermal; forms at relatively low temperatures through the deposition of silica from groundwater in the cavities of igneous rocks
About This Crystal
A translucent to semi-opaque variety of chalcedony. The specimen shown is a tumbled or water-worn pebble with a waxy to vitreous luster, displaying a warm orange to reddish-brown hue. It features subtle internal cloudiness and small dark mineral inclusions typical of natural carnelian.
Physical Characteristics
Color: Orange, red, brownish-red; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Fluorescence: Weak yellowish-white or inert
Optical Properties
Refractive Index: 1.530–1.540; Birefringence: Up to 0.004; Pleochroism: None; Optical Character: Uniaxial positive; Lacks dispersion or specific phenomena like stars
Hardness & Durability
Origin Region
India, Brazil, Uruguay, Madagascar, and Egypt; typically found in volcanic cavities and sedimentary alluvial deposits
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Very High (due to cryptocrystalline structure); Stability: Excellent, though high heat can deepen color
Care & Maintenance
Safe to clean with warm soapy water and soft brushes. Generally safe for ultrasonic cleaners. Avoid prolonged exposure to extreme heat and harsh acids.
Rarity & Value
Common; Value is determined by color intensity and transparency. Untreated brownish stones are often heat-treated to enhance the red/orange saturation. Generally affordable.
Special Characteristics
Color originates from iron oxide impurities (Hematite/Goethite). Exhibits a characteristic 'waxy' luster on fractured surfaces and a smooth, even texture when polished.
Lore & History
Historically significant in Ancient Egypt where it was used in amulets and 'The Book of the Dead'. In Rome, it was used for signet rings due to its non-stick property with wax. Traditionally associated with the Sacral Chakra, motivation, and endurance.