Turquoise
Turquoise · Semi-Precious Gemstone
Crystal System
Triclinic, typically forms massive, cryptocrystalline, or nodular habits rather than distinct individual crystals
Mineral Group
Phosphates
Chemical Formula
CuAl6(PO4)4(OH)8·4H2O
Formation Process
Supergene/secondary formation process involving the weathering and oxidation of pre-existing copper minerals and apatite in arid climates, occurring near the surface at low temperatures and pressures.
About This Crystal
A tumbled, smooth specimen displaying a vivid robins-egg blue to greenish-blue color with dark brown to black spiderweb matrix veins running through the stone. It is opaque with a waxy to sub-vitreous luster.
Physical Characteristics
Color ranges from blue to green; streak is white or pale green. Cleavage is good in one direction and fair in another, but rarely seen due to massive habit. Fracture is conchoidal to uneven. Specific gravity is approximately 2.60 to 2.90. Brittle tenacity. May show weak green to yellow-green fluorescence under UV light.
Optical Properties
Refractive index ranges from 1.61 to 1.65. Birefringence is 0.040. Optically biaxial positive. Shows no pleochroism due to its microcrystalline aggregate nature.
Hardness & Durability
Origin Region
Notable sources include the Southwestern United States, Iran, China, Egypt (Sinai Peninsula), and Mexico. Forms in arid regions where acidic groundwater reacts with copper-bearing minerals.
Hardness & Durability
Mohs hardness of 5 to 6, making it moderately soft and vulnerable to scratching. Fair to poor toughness. Porous nature makes it sensitive to chemicals, oils, cosmetics, and prolonged heat.
Care & Maintenance
Clean gently with warm, soapy water and a soft cloth. Never use ultrasonic cleaners, steam, or harsh chemical detergents. Store separately in a soft pouch away from harder gemstones and direct sunlight.
Rarity & Value
Uncommon to Rare depending on grade and matrix pattern. High-grade natural, untreated turquoise with spiderweb matrix commands high prices. Treatments such as stabilization, impregnation with resin, and dyeing are very common to enhance durability and color.
Special Characteristics
Often features intricate matrix patterns (limonite or sandstone host rock remnants) forming spiderweb patterns. Highly porous structure that absorbs skin oils, which can gradually alter the color over time.
Lore & History
Used by ancient civilizations including the Egyptians, Native Americans, and Persians as a protective amulet, talisman of kings, and symbol of wealth and health. Traditionally associated with the Throat Chakra, believed to promote communication, healing, and spiritual grounding.