Turquoise
Turquoise · Semi-Precious Gemstone / Ornamental Mineral
Crystal System
Triclinic, massive or microcrystalline habit, typically occurring as crusts, nodular masses, or veins.
Mineral Group
Phosphates (specifically an anhydrous phosphate containing copper and aluminum)
Chemical Formula
CuAl6(PO4)4(OH)8·4H2O
Formation Process
Supergene / Secondary depositional process, forming via the weathering and oxidation of pre-existing copper and aluminum minerals in arid hydrothermal or volcanic environments near the Earth's surface.
About This Crystal
The specimen is a shield- or triangular-shaped cabochon set in a silver ring, displaying a rich blue-green to teal body color. It features distinct dark brown to black web-like matrix veins running through the stone, creating a classic spiderweb pattern characteristic of natural turquoise.
Physical Characteristics
Color ranges from robin's egg blue to greenish-blue with brown or black limonite/matrix veins; streak is white to pale greenish-blue; cleavage is good in two directions (rarely seen in gems); fracture is conchoidal to uneven; specific gravity is approximately 2.60 to 2.86; tenacity is brittle; exhibits weak to moderate pale green or yellow-green fluorescence under longwave UV light.
Optical Properties
Refractive index ranges from 1.61 to 1.65; it is biaxial optically positive with low birefringence; typically opaque with a waxy to sub-vitreous luster; non-pleochroic due to its microcrystalline aggregate nature.
Hardness & Durability
Origin Region
Notable sources include the Southwestern United States (Arizona, Nevada, New Mexico), Iran (Nishapur), China, and Sinai (Egypt). It forms in arid regions where acidic, copper-rich groundwater reacts with aluminum- and potassium-bearing minerals.
Hardness & Durability
Mohs hardness of 5 to 6, making it moderately soft and susceptible to scratching by harder materials and quartz; toughness is fair to poor depending on porosity; sensitive to heat, acids, skin oils, and cosmetics which can alter or discolor the stone.
Care & Maintenance
Clean gently with warm, soapy water and a soft cloth; avoid ultrasonic cleaners, steam cleaners, harsh chemicals, perfumes, oils, and prolonged exposure to direct sunlight or high heat, which can cause dehydration and discoloration.
Rarity & Value
Uncommon to Rare depending on grade, spiderweb matrix, and geographical origin (such as high-grade natural Bisbee or Sleeping Beauty turquoise); value is determined by color purity (robin's egg blue is most prized), absence of chalky softness, matrix patterns, and lack of stabilization treatments; treatments like resin stabilization or enhancement are very common.
Special Characteristics
Notable for its distinctive web-like matrix (spiderweb turquoise), high copper-derived color variations, and porous nature which allows it to absorb oils from skin and environment, occasionally changing color over decades of wear.
Lore & History
Historically revered by ancient civilizations including the Egyptians, Native Americans, and Persians as a sacred stone of protection, good fortune, and healing. Used in ceremonial jewelry, amulets, and burial adornments. In modern crystal healing, it is traditionally associated with the throat chakra, symbolizing communication, spiritual grounding, and emotional balance, though these are cultural traditions rather than scientifically validated effects.