Carnelian
Chalcedony var. Carnelian (Cryptocrystalline Quartz) · Semi-Precious Gemstone
Crystal System
Trigonal (Hexagonal sub-system); usually occurs in massive, botryoidal, or microcrystalline aggregates rather than distinct crystals.
Mineral Group
Silicates (Tectosilicate subgroup; Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide with Iron Oxide Fe2O3 trace impurities)
Formation Process
Formed at low temperatures through the deposition of silica from groundwater in the cavities of igneous rocks (mainly volcanic lavas and basalts) or sedimentary formations.
About This Crystal
A translucent to semi-opaque chalcedony silica. It typically exhibits a vitreous to waxy luster and occurs in varying shades of orange, reddish-orange, and brownish-red. This specimen is a polished tumble stone showing a warm apricot-orange hue with internal cloudy inclusions and slight iron-rich banding.
Physical Characteristics
Color: Orange to reddish-brown; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Tenacity: Brittle but tough due to microcrystalline structure. Non-fluorescent usually.
Optical Properties
Refractive Index: 1.530–1.540; Birefringence: up to 0.004; Optical character: Uniaxial positive; It does not show pleochroism or dispersion but can exhibit subtle banding and translucency.
Hardness & Durability
Origin Region
Notable sources include India (Gujarat), Brazil, Uruguay, Madagascar, and Botswana. Often found in volcanic cavities and sedimentary environments.
Hardness & Durability
Mohs Hardness: 6.5–7. Highly durable with no cleavage, making it excellent for all types of jewelry including rings. Resistant to most household scratching.
Care & Maintenance
Wash with warm soapy water and a soft brush. Avoid harsh chemicals and sudden temperature shifts. Generally stable in sunlight, though some dyed varieties (common in commerce) may fade over long exposure.
Rarity & Value
Common. Value is determined by color intensity (deeper reds are preferred), translucency, and lack of internal fractures. Frequently treated/stained with iron salts and heated to enhance the red color.
Special Characteristics
Known for its distinct iron-oxide coloring; may show 'carnelian spots' or subtle banding typical of chalcedony. Some specimens show a faint 'cloudy' or 'milky' interior beneath the surface luster.
Lore & History
Historically used by ancient Egyptians for amulets (Book of the Dead) and by Romans for signet rings because hot wax does not stick to it. Symbolically associated with the Sacral Chakra, vitality, motivation, and endurance in traditional lore.