Carnelian
Quartz var. Carnelian (Chalcedony) · Semi-Precious Gemstone and Decorative Stone
Crystal System
Trigonal, microcrystalline (cryptocrystalline quartz aggregate, forming in massive, nodular, or tumbled habits)
Mineral Group
Silicates (Subgroup: Tectosilicates)
Chemical Formula
SiO2
Formation Process
Sedimentary or Hydrothermal. Forms at low temperatures from silica-rich groundwater depositing microscopic quartz crystals in cavities, often colored by iron oxide impurities.
About This Crystal
A smooth, tumbled, polished stone displaying warm reddish-orange to brownish-red hues. It is translucent to semi-translucent with a vitreous to waxy luster. Subtle banding or color zoning is characteristic of chalcedony varieties.
Physical Characteristics
Color ranges from yellowish-orange to deep brownish-red. Streak is white. Cleavage is none due to cryptocrystalline structure. Fracture is conchoidal to uneven. Specific gravity is approximately 2.58 to 2.64. Tenacity is brittle.
Optical Properties
Refractive index ranges from 1.543 to 1.554. Birefringence is weak (0.004 to 0.009). Doubly refractive (aggregate polarization). Pleochroism is generally not distinct due to microcrystalline nature.
Hardness & Durability
Origin Region
Notable sources include India, Brazil, Uruguay, Madagascar, and the United States. Forms typically in volcanic cavities, hydrothermal veins, and sedimentary environments.
Hardness & Durability
Mohs hardness of 6.5 to 7. Toughness is good due to the interlocking microfibrous structure, making it highly durable for everyday jewelry wear.
Care & Maintenance
Easy to care for. Clean safely using warm soapy water and a soft cloth. Avoid harsh chemical cleaners and prolonged, direct exposure to intense sunlight to prevent minor fading over long periods.
Rarity & Value
Common and widely accessible. Value is determined by color intensity, uniformity, transparency, and size. Highly affordable, though exceptional translucent deep-red specimens command higher collector values. Heat treatment and dyeing are sometimes used commercially to enhance color.
Special Characteristics
Displays characteristic subtle cloud-like or banded internal patterns caused by micro-inclusions of iron oxides and hydroxides such as hematite and goethite.
Lore & History
Historically used by ancient civilizations including the Egyptians, Romans, and Greeks for signet rings, amulets, and royal jewelry. In traditional crystal healing lore, Carnelian is associated with the Sacral Chakra, believed to boost courage, vitality, motivation, and creativity. Note: These are traditional and cultural beliefs, not scientifically validated properties.