Turquoise
Turquoise · Semi-Precious Gemstone
Crystal System
Triclinic, typically found in massive, microcrystalline, or botryoidal habits
Mineral Group
Phosphates, specifically the turquoise group
Chemical Formula
CuAl6(PO4)4(OH)8·4H2O
Formation Process
Secondary mineral formed by the action of meteoric waters percolating through copper-bearing aluminum-rich rocks in arid climates
About This Crystal
An opaque, blue-to-green cabochon gemstone featuring a characteristic robin's egg blue or greenish-blue color with a waxy-to-subvitreous luster, often accented by dark matrix web veins
Physical Characteristics
Color ranges from bright blue to yellowish-green; white streak; no distinct cleavage; conchoidal to uneven fracture; specific gravity around 2.60-2.90; brittle tenacity
Optical Properties
Biaxial (+), refractive index of approximately 1.61 to 1.65, generally opaque with no notable pleochroism
Hardness & Durability
Origin Region
North America (Arizona, Nevada, New Mexico), Iran, Egypt, and China
Hardness & Durability
Mohs hardness of 5 to 6; fair to poor toughness; sensitive to heat, acids, skin oils, and cosmetics which can alter the color
Care & Maintenance
Clean gently with warm, soapy water; avoid ultrasonic cleaners, steam, harsh chemicals, oils, and prolonged exposure to direct sunlight or cosmetics
Rarity & Value
Uncommon to rare depending on grade, natural clarity, and spiderweb matrix patterns; high-grade spiderweb turquoise commands high collector prices, while stabilized and treated stones are common and affordable
Special Characteristics
Often features intricate matrix patterns caused by surrounding host rock, such as limonite or sandstone, creating spiderweb effects
Lore & History
Historically revered by ancient Egyptians, Persians, and Native Americans as a sacred stone of protection, good fortune, and healing; traditionally associated with the throat chakra in metaphysical practices