Turquoise
Turquoise (Copper Aluminum Phosphate) · Semi-Precious Gemstone
Crystal System
Triclinic; typically occurs in cryptocrystalline, massive, or nodules (botryoidal) habits
Mineral Group
Phosphates
Chemical Formula
CuAl6(PO4)4(OH)8·4H2O
Formation Process
Secondary mineralization through the hydrothermal alteration of aluminum-rich rocks in arid environments
About This Crystal
An opaque, sky-blue to blue-green stone with a waxy to sub-vitreous luster, often featuring a dark matrix of limonite or manganese oxide
Physical Characteristics
Sky-blue color, white to greenish-white streak, no visible cleavage in massive forms, conchoidal to splintery fracture, specific gravity of 2.6-2.9, often fluorescent under longwave UV
Optical Properties
Opaque, mean refractive index of approximately 1.61 to 1.65, biaxial positive (rarely measured in massive specimens), no pleochroism due to opacity
Hardness & Durability
Origin Region
Arizona and New Mexico (USA), Iran (Nishapur), China, and Egypt (Sinai Peninsula)
Hardness & Durability
Mohs hardness 5 to 6; brittle tenacity, fair to good toughness depending on porosity, sensitive to high heat and acids
Care & Maintenance
Clean with warm soapy water only; avoid ultrasonic or steam cleaners; store away from skin oils, perfumes, and direct sunlight to prevent discoloration
Rarity & Value
Common to Rare (Sleeping Beauty or Persian qualities are rare); price varies by matrix pattern and color saturation; often stabilized with resin or wax
Special Characteristics
Matrix patterns (Spiderweb), cryptocrystalline structure, porous nature allowed for ancient dyeing and modern stabilization techniques
Lore & History
Used by ancient Egyptian, Aztec, and Native American cultures as a stone of protection, leadership, and connection to the sky and water