Blue Chalcedony
Quartz var. Chalcedony · Semi-Precious Gemstone
Crystal System
Trigonal, microcrystalline (cryptocrystalline) aggregate habit forming massive or tumbled stones with fibrous structures
Mineral Group
Silicates, specifically Tectosilicates
Chemical Formula
SiO2
Formation Process
Hydrothermal and low-temperature sedimentary processes involving silica-rich groundwaters depositing microscopic quartz crystals in cavities, fractures, and nodules
About This Crystal
A polished, tumbled smooth stone displaying a pale milky-blue to greenish-blue color with subtle translucent banding and swirling white inclusions characteristic of cryptocrystalline quartz, exhibiting a waxy to vitreous luster
Physical Characteristics
Color is pale blue to greyish-blue; streak is white; cleavage is absent due to microcrystalline structure; fracture is conchoidal to uneven; specific gravity is approximately 2.58 to 2.66; tenacity is brittle
Optical Properties
Singly or doubly refractive microcrystalline aggregate, refractive index ranges from 1.530 to 1.540, birefringence is weak, generally inert or weak greenish under UV light
Hardness & Durability
Origin Region
Notable sources include Namibia, Turkey, USA (Oregon, California), Brazil, and Madagascar; typically forms in low-temperature hydrothermal veins and volcanic cavities
Hardness & Durability
Mohs hardness is 6.5 to 7, making it durable for general jewelry use with good toughness and resistance to scratching, though care should be taken with sudden temperature shocks
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid harsh chemical cleaners, prolonged direct sunlight to prevent potential color fading, and ultrasonic cleaners if fractures are present
Rarity & Value
Common to uncommon depending on the intensity and saturation of the blue color; high-grade natural saturated blue chalcedony from regions like Turkey can command higher collector prices, while standard pale varieties are affordable
Special Characteristics
Exhibits subtle internal color banding, translucency with milkiness, and sometimes chatoyancy or a glowing effect known as the chalcedony light scatter
Lore & History
Historically used by ancient civilizations for seals, signet rings, and carvings; in traditional crystal healing, blue chalcedony is associated with the throat chakra, tranquility, emotional balance, and communication, though these are strictly cultural and spiritual beliefs without scientific validation