Turquoise
Turquoise · Semi-Precious Gemstone / Ornamental Stone
Crystal System
Triclinic, typically occurs in massive, microcrystalline, or botryoidal habits rather than distinct individual crystals
Mineral Group
Phosphates
Chemical Formula
CuAl6(PO4)4(OH)8·4H2O
Formation Process
Secondary formation via hydrothermal alteration or supergene weathering processes, typically occurring near the surface in arid climates where descending meteoric waters react with pre-existing copper and aluminum minerals.
About This Crystal
The specimen is a small, tumbled stone featuring a vibrant, robin-egg blue to greenish-blue patch contrasted against a pale whitish matrix, interspersed with dark brown to black web-like matrix veins (limestone or host rock remnants). It has a waxy to sub-vitreous luster and is opaque.
Physical Characteristics
Color ranges from bright sky blue to pale blue-green with brownish-black matrix web inclusions; streak is white to pale greenish-blue; perfect to good cleavage in two directions (rarely observed due to massive habit); fracture is conchoidal to uneven; specific gravity is 2.60 to 2.85; tenacity is brittle; may exhibit weak yellowish-green fluorescence under shortwave UV light.
Optical Properties
Refractive index ranges from 1.61 to 1.65 (birefringence around 0.040); typically aggregate or doubly refractive under the polariscope; pleochroism is weak to non-existent in mass; displays no notable dispersion or special optical phenomena aside from potential spiderweb matrix patterns.
Hardness & Durability
Origin Region
Notable sources include Iran (Nishapur), the Southwestern United States (Arizona, Nevada, New Mexico), Egypt (Sinai Peninsula), and China. Forms in arid regions where acidic groundwater percolates through copper-bearing aluminum-rich rocks.
Hardness & Durability
Mohs hardness of 5 to 6, making it moderately soft and susceptible to scratching by harder materials like quartz; toughness is fair to poor depending on porosity; sensitive to chemicals, oils, cosmetics, perspiration, and prolonged heat or direct sunlight which can cause discoloration.
Care & Maintenance
Clean gently using 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. Store separately from harder gemstones to prevent scratching.
Rarity & Value
Uncommon to rare depending on grade and origin (e.g., high-grade untreated Persian or American spiderweb turquoise is highly valuable); value is determined by color intensity, matrix pattern, absence of treatments, and size; enhancements such as stabilization, impregnation with resin, and dyeing are very common.
Special Characteristics
Often features characteristic dark limonite or sandstone webbing (spiderweb turquoise) which adds unique aesthetic appeal and helps distinguish natural variations from synthetic substitutes.
Lore & History
Used for thousands of years by ancient civilizations including the Egyptians, Native Americans, and Persians as a protective amulet, symbol of wealth, and talisman of healing. In modern metaphysical practices, it is traditionally associated with the Throat Chakra, believed to promote spiritual attunement, inner calm, and enhanced communication.