Carnelian
Chalcedony var. Carnelian · Semi-Precious Gemstone / Decorative Stone
Crystal System
Trigonal (Hexagonal) crystal system; Cryptocrystalline (microscopic fibrous) habit, shown here as a polished sphere
Mineral Group
Silicates (Tectosilicate subgroup / Quartz group)
Chemical Formula
SiO2 (Silicon Dioxide) colored by iron oxide (Hematite) impurities
Formation Process
Hydrothermal/Sedimentary process: Silicic acid precipitates in cavities of volcanic rocks or sedimentary environments at relatively low temperatures
About This Crystal
A polished translucent to semi-opaque sphere exhibiting a deep reddish-orange to brownish-red color. It features a waxy to vitreous luster with a visible lighter internal band or fracture line that reflects light.
Physical Characteristics
Color: Red-orange; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.58–2.64; Tenacity: Brittle but tough; typically non-fluorescent
Optical Properties
Refractive Index: 1.530–1.540; Birefringence: Up to 0.009; Optically uniaxial positive; Diaphaneity: Translucent to opaque; No pleochroism
Hardness & Durability
Origin Region
Prominent sources include Brazil, Uruguay, India, Madagascar, and Botswana; often forms in volcanic cavities or as alluvial pebbles
Hardness & Durability
Mohs Hardness: 6.5–7; Excellent durability and toughness for jewelry use due to its microcrystalline structure
Care & Maintenance
Clean with warm soapy water and a soft brush; generally stable, though prolonged high heat can enhance color or potentially cause fractures; avoid harsh chemicals
Rarity & Value
Common; Value is driven by color saturation and clarity; vibrant orange-red specimens are most prized; heat treatment of pale chalcedony to create carnelian is very common
Special Characteristics
Translucency combined with iron-oxide staining creates a warm, glowing internal effect; may exhibit faint banding resembling agate
Lore & History
Historically used in ancient Egypt for amulets and in Rome for signet rings (as wax doesn't stick to it). Metaphysically associated with the Sacral Chakra, vitality, and courage.