Carnelian
Quartz var. Carnelian · Semi-Precious Gemstone / Ornamental Stone
Crystal System
Trigonal/Hexagonal; usually occurs in microcrystalline massive habits or as rounded pebbles, rarely as distinct large crystals.
Mineral Group
Silicates (Subgroup: Tectosilicates)
Chemical Formula
SiO2 (Silicon Dioxide) with Iron Oxide (Fe2O3) impurities
Formation Process
Primarily hydrothermal; forms when silica-rich fluids precipitate at low temperatures within cavities (vugs) of volcanic rocks (basalts/andesites) or sedimentary environments.
About This Crystal
A translucent to semi-opaque variety of chalcedony. This specific specimen exhibits a warm orange-brown hue with a vitreous to waxy luster. It shows internal cloudiness and a darker, reddish-brown iron-rich inclusion or banding across the center.
Physical Characteristics
Color: Pale orange to deep reddish-brown; Streak: White; Cleavage: None; Fracture: Conchoidal to uneven; Specific Gravity: 2.58–2.64; Fluorescence: Weak greenish or inert under UV.
Optical Properties
Refractive Index: 1.530–1.540; Birefringence: Weak; Pleochroism: None; Optical Character: Aggregates are singly refractive in practice due to microcrystalline structure.
Hardness & Durability
Origin Region
Major sources include India (Gujarat), Brazil, Uruguay, Madagascar, and Botswana. Historically significant sources in Egypt and the Arabian Peninsula.
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Excellent (highly resistant to chipping or breaking due to its interlocking fibrous structure); Stability: Stable.
Care & Maintenance
Clean with warm soapy water and a soft brush; safe for ultrasonic cleaning if no significant fractures are present. Store away from harder stones like diamonds or sapphires to prevent scratching.
Rarity & Value
Common; Value is determined by color saturation (deep red-orange is preferred) and translucency. Most commercially available carnelian is heat-treated or dyed agate to enhance color.
Special Characteristics
Often displays subtle banding when held to light; color is caused by hematite (iron) inclusions. Translucency varies significantly within a single tumbled stone.
Lore & History
Historically used in ancient Egypt for amulets and signet rings (Book of the Dead significance) and by Roman soldiers for courage. Symbolically associated with the Sacral Chakra, vitality, and creative energy.