amorphous Phosphates
Turquoise (Massive (typical))
CuAl6(PO4)4(OH)8.4H2O
Crystal Structure
#! Species: Turquoise
#! System: Amorphous (cryptocrystalline)
#! Habit: Massive and nodular aggregates
amorphous[cryptocrystalline]:{massive, nodular}[colour:blue]
amorphous
-1
{massive, nodular}
Quick Facts
Hardness
5.0
Specific Gravity
2.6
Refractive Index
1.61
Optical Character
Biaxial +
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Open in PlaygroundPhysical Properties
Crystal Systemamorphous
Hardness (Mohs)5.0
Specific Gravity2.6
CleavageGood {001}, poor {010}
FractureConchoidal to smooth
LustreWaxy to sub-vitreous
Optical Properties
Refractive Index1.61
Birefringence0.04
Optical CharacterBiaxial +
PleochroismNone (typically aggregate)
Colours
Sky blue (Persian blue - most valued)Blue-greenGreenish-blueApple greenWith matrix patterns
Localities
Iran (Nishapur - finest Persian blue)USA (Arizona, Nevada, New Mexico)Egypt (Sinai - historic)China (Hubei)TibetMexico
Known Treatments
Stabilization (most material)Wax/oil impregnationZachery processDyeingReconstitution
Crystal Forms
massivenodularveins
Notes
Most commercial turquoise is stabilized; untreated gem-quality material commands premium prices
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Open in PlaygroundSynthetics & Simulants
Known synthetic and simulant versions of Turquoise (Massive (typical))
Related Minerals
Other minerals in the amorphous system
Ambroid (Pressed Amber)
Compressed and fused amber chips (same chemical composition as amber — fossil resin; succinite for Baltic amber)
Bone (Ivory Simulant)
Ca5(PO4)3(OH) (hydroxyapatite; same general composition as ivory dentine) in collagen matrix; technically microcrystalline hydroxyapatite but gemologically treated as amorphous/aggregate biomineral
Chalcedony (Botryoidal)
SiO2
Chalcedony (Massive)
SiO2
Chrysocolla
(Cu,Al)2H2Si2O5(OH)4.nH2O
Copal (Amber Simulant)
Partially polymerised plant resin (labdanoid diterpenes; younger resin; not fully matured/polymerised)