Carnelian
Quartz variety Carnelian · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Trigonal; Cryptocrystalline (microscopic fibrous structure) typically occurring in massive or nodular habits
Mineral Group
Silicates; Tectosilicate subgroup (Chalcedony species)
Chemical Formula
SiO2 (Silicon Dioxide) with impurities of iron oxide (hematite)
Formation Process
Sedimentary or Hydrothermal; forms at relatively low temperatures through the deposition of silica from groundwater into cavities in volcanic or sedimentary rocks
About This Crystal
A translucent to semi-opaque variety of chalcedony with a waxy luster. It exhibits a range of warm colors from pale orange and brownish-red to deep sunset orange. The polished specimen shown is a rounded tumble with consistent vitreous-to-waxy luster and subtle color clouding.
Physical Characteristics
Color: Orange to reddish-brown; Streak: White; Cleavage: None; Fracture: Conchoidal (shell-like); Specific Gravity: 2.58–2.64; Fluorescence: Weak to inert under UV light
Optical Properties
Refractive Index: 1.530–1.540; Birefringence: Up to 0.004; Pleochroism: None; Singly refractive (aggregate); dispersion is low
Hardness & Durability
Origin Region
Notable sources include Brazil, India, Madagascar, Uruguay, and Botswana; typically found in volcanic cavities and sedimentary environments
Hardness & Durability
Mohs Hardness: 6.5–7; Toughness: Excellent; Very durable for jewelry and daily wear; stable under light and most chemicals
Care & Maintenance
Clean with warm soapy water and a soft brush; ultrasonic cleaners are generally safe if there are no significant fractures; store away from harder gems like diamonds to avoid scratching
Rarity & Value
Common and widely available; value is determined by color intensity and translucency; often heat-treated to enhance red tones or dyed from common grey chalcedony
Special Characteristics
Exhibits translucency when backlit; can show subtle banding which may transition into agate; iron oxide content creates its distinctive red-orange hue
Lore & History
Historically used by ancient Egyptians as a stone of vitality and by Romans in signet rings; traditionally associated with the Sacral Chakra and believed to promote courage, motivation, and creative energy