Turquoise
Turquoise · Semi-Precious Gemstone
Crystal System
Triclinic, typically occurs as massive, microcrystalline aggregates, nodular, vein filling, or botryoidal forms.
Mineral Group
Phosphates
Chemical Formula
CuAl6(PO4)4(OH)8·4H2O
Formation Process
Supergene/secondary alteration process involving the weathering and oxidation of pre-existing copper and aluminum deposits, typically occurring at shallow depths in arid or desert climates.
About This Crystal
A polished, tumbled smooth stone displaying a vibrant, vivid robin-egg to sky-blue color with subtle mottled variations. It has a sub-vitreous to waxy luster, is opaque, and shows minor matrix or lighter color shading typical of natural tumbled turquoise.
Physical Characteristics
Color ranges from bright blue to greenish-blue; streak is white to pale greenish-blue. Cleavage is imperfect in two directions. Fracture is conchoidal to uneven. Specific gravity ranges from 2.60 to 2.90. Tenacity is brittle.
Optical Properties
Biaxial positive with a refractive index around 1.61 to 1.65. Generally non-pleochroic due to microcrystalline massive structure. Displays no notable special optical phenomena like chatoyancy or asterism.
Hardness & Durability
Origin Region
Notable sources include Iran (Nishapur), the southwestern United States (Arizona, Nevada, New Mexico), Sinai Peninsula, and China. Forms in arid regions where acidic copper-rich groundwater interacts with aluminum and phosphorus-bearing minerals.
Hardness & Durability
Mohs hardness of 5 to 6. Toughness is fair to poor depending on porosity. Sensitive to acids, oils, cosmetics, perspiration, and prolonged direct heat which can cause discoloration or dehydration.
Care & Maintenance
Clean gently with warm, soapy water and a soft cloth. Never use ultrasonic cleaners, steam, or harsh chemical solvents. Store separately from harder gemstones to avoid scratching and keep away from prolonged direct sunlight and oils.
Rarity & Value
Uncommon to rare depending on grade and origin. Value is determined by intense pure blue color, minimal webbed matrix, absence of plastic stabilization treatments, and historical source like Persian material. Enhanced or stabilized stones are common and affordable.
Special Characteristics
May exhibit weak pale green fluorescence under shortwave UV light. Highly porous natural variations can absorb skin oils, gradually altering the stone's color over time.
Lore & History
Historically revered by ancient Egyptians, Native Americans, and Persians as a sacred stone of protection, good fortune, and healing. Associated traditionally with the throat chakra, it is believed in modern crystal lore to promote communication, wisdom, and inner calm.