Blue Chalcedony
Quartz var. Chalcedony · Semi-Precious Gemstone and Decorative Stone
Crystal System
Trigonal, microcrystalline (cryptocrystalline) aggregate habit, forming in botryoidal, mammillary, or massive crusts.
Mineral Group
Silicates, specifically Tectosilicates
Chemical Formula
SiO2
Formation Process
Hydrothermal and low-temperature deposition from silica-rich aqueous solutions, often filling cavities in volcanic lavas.
About This Crystal
A polished, tumbled smooth specimen of a pale to medium grayish-blue color. It has a translucent to semi-translucent appearance with a waxy to vitreous luster, displaying subtle internal cloudiness and minor lighter patches.
Physical Characteristics
Color is pale blue to lavender-blue, white streak, conchoidal fracture, distinct lack of visible cleavage due to microcrystalline structure, specific gravity around 2.60 to 2.65, brittle tenacity, generally inert to magnetism and UV fluorescence.
Optical Properties
Refractive index ranges from 1.530 to 1.540, doubly refractive (aggregate birefringence), uniaxial positive, lacks strong pleochroism due to cryptocrystalline nature.
Hardness & Durability
Origin Region
Found globally with notable deposits in Namibia, Turkey, USA, Madagascar, and Brazil. Typically forms in low-temperature hydrothermal veins and cavities in volcanic rocks.
Hardness & Durability
Mohs hardness of 6.5 to 7, good toughness due to microcrystalline interlocking fibers, making it quite durable and suitable for everyday jewelry use with proper care.
Care & Maintenance
Safe to clean with warm soapy water and a soft brush. Avoid harsh chemical cleaners, prolonged exposure to extreme heat, and ultrasonic cleaners if fractures are present. Store separately to prevent scratching softer stones.
Rarity & Value
Common to uncommon depending on color saturation and translucency. Affordable and widely available on the market, with prices varying based on size, cut, and purity of color. Enhancements like dyeing are occasionally seen for lower-grade material.
Special Characteristics
Microfibrous structure (quartz and moganite intergrowths), smooth polished finish enhancing its waxy luster and translucent depth.
Lore & History
Historically used by ancient civilizations for amulets and seals. In modern crystal healing traditions, blue chalcedony is associated with the throat chakra, symbolizing calm, communication, and emotional balance, though these are traditional beliefs rather than scientific claims.