Mineral - Zunyite
Zunyite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
Al₁₃Si₅O₂₀(OH,F)₁₈Cl
Unit Cell
a=13.88 Z=4
Physical Properties
Hardness
7
Streak
white
Density
Normal (2-3,5)
Cleavage
Distinct after {111}
Fracture
Tenacity
Brittle
Optical Properties
Color
grayred
Birefringence
Luster
Vitreous
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
isometric
Point Group
hextetrahedral - 4 3m
Space Group
F 4 3m (216)
Habit
dodecahedron, Octahedron, Tetrahedron
Formation
(1) In hydrothermal systems with high silica supersaturation and high fluorine and chlorine content, through the alteration of aluminosilicates in the advanced argillitic transformation zone.
(2) By contact metasomatism in skarns or boron-rich metasomatites, through the reaction of fluoride-bearing fluids with aluminum-rich host rocks.
Paragenesis
Twinning
Contact- and Penetration twins after {111}
Rarity
Rather rare
Synonyms
Zunyite
Composition
Elements
Mass
SiO₂
24.33
Al₂O₃
57.88
Fe₂O₃
0.20
Li₂O
0.01
Na₂O
0.24
K₂O
0.10
F
5.61
Cl
2.91
H₂O
10.89
P₂O₅
0.60
O=(F,Cl)₂
3.02
Colorado (Dana 1895)