Blue Chalcedony
Quartz var. Chalcedony · Semi-Precious Gemstone
Crystal System
Trigonal, microcrystalline habit forming compact masses, botryoidal, or nodular structures
Mineral Group
Silicates (Tectosilicates)
Chemical Formula
SiO2
Formation Process
Hydrothermal and low-temperature aqueous deposition, precipitating from silica-rich solutions in cavities and fractures
About This Crystal
Spherical polished beads showing translucent to semi-translucent body with distinct blue and white banding or mottled patches, vitreous to waxy luster, displaying characteristic cloud-like internal patterns and variable color zoning
Physical Characteristics
Color ranges from light sky blue to deep indigo with white translucent zones; white streak; no true cleavage; conchoidal fracture; specific gravity around 2.60 to 2.65; brittle tenacity; generally inert under UV light
Optical Properties
Uniaxial positive with refractive index around 1.544-1.553, double refraction (birefringence) of 0.009, typically displays aggregate optical character with no significant pleochroism
Hardness & Durability
Origin Region
Found globally with notable sources in Brazil, India, Madagascar, and the USA; forms in hydrothermal veins and cavities in volcanic rocks
Hardness & Durability
Mohs hardness of 6.5 to 7, good toughness due to microcrystalline interlocking structure, stable against most chemicals except hydrofluoric acid, suitable for everyday jewelry wear
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners and harsh chemicals; store separately in a soft pouch to prevent scratching softer stones; generally stable in sunlight
Rarity & Value
Common to uncommon depending on color saturation and translucency; value determined by uniformity of color, clarity, and bead size; commonly dyed to enhance blue color, though natural specimens are widely available
Special Characteristics
May exhibit a slight chatoyant effect or adularescence-like sheen depending on internal fiber orientation and micro-inclusions
Lore & History
Historically used in ancient seals and carvings across Mediterranean civilizations; associated with calming energy, communication, and emotional balance in modern crystal healing traditions tied to the throat chakra