Mineral - Turquoise
Turquoise
Chemical Properties
Mineral Class
Phosphates
Toxicity
none
Formula
CuAl₆(PO₄)₄(OH)₈ · 4H₂O
Unit Cell
a=7.41 b=9.91 c=7.64 α=111° β=115° γ=70° Z=1
Physical Properties
Hardness
5 - 6
Streak
whitegreengreen white
Density
Normal (2-3,5)
Cleavage
Perfect after {001}, distinct after {010}
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
greenblue
Birefringence
0.040
Luster
Waxy
Transparency
translucent,
transparent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
triclinic
Point Group
triclinic-pinacoidal - 1
Space Group
P 1 (2)
Habit
coarse, earthy, spherical, massive, grape-shaped
Formation
Secondary, in the oxidation zone of supergene deposits, where copper-bearing rocks react with phosphate-bearing surface waters in arid to semiarid climates
Paragenesis
Twinning
Rarity
Common
Synonyms
Turquoise
Composition
Elements
Mass
P₂O₅
34.13
Al₂O₃
36.50
Fe₂O₃
0.21
CuO
9.00
H₂O
20.12
Virginia (Palache et al. 1952)
Groups and Members
Turquoise-Group