triclinic Phosphates
Turquoise (Crystal form (rare))
Formula CuAl6(PO4)4(OH)8.4H2O
Crystal Structure
#! Species: Turquoise
#! System: Triclinic (-1)
#! Habit: Prismatic crystals (extremely rare)
triclinic[-1]:{010}@1.0 + {001}@0.9 + {110}@0.7
triclinic
-1
{010} {001} {110}
Quick Facts
Hardness
5.0
Specific Gravity
2.6
Refractive Index
1.61
Optical Character
Biaxial +
Physical Properties
- Crystal System
- triclinic
- Hardness (Mohs)
- 5.0
- Specific Gravity
- 2.6
- Cleavage
- Good {001}, poor {010}
- Fracture
- Conchoidal to smooth
- Lustre
- Waxy to sub-vitreous
Optical Properties
- Refractive Index
- 1.61
- Birefringence
- 0.04
- Optical Character
- Biaxial +
- Pleochroism
- None (typically aggregate)
Characteristics
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
pinacoidprism
Notes
Extremely rare crystal form; the vast majority of turquoise is cryptocrystalline massive
Synthetics & Simulants
Known synthetic and simulant versions of Turquoise
Related Minerals
Other minerals in the triclinic system
