Mineral - Sugilite
Sugilite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
KNa₂Fe³⁺₂Li₃[Si₁₂O₃₀]
Unit Cell
a=10.01 c=14.00 Z=2
Physical Properties
Hardness
5.5 - 6.5
Streak
white
Density
Normal (2-3,5)
Cleavage
Indistinct after {0001}
Fracture
Tenacity
Optical Properties
Color
violet
Birefringence
0.005
Luster
Vitreous
Transparency
translucent,
transparent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
hexagonal
Point Group
dihexagonal-dipyramidal - 6/m 2/m 2/m
Space Group
P6/mcc (192)
Habit
coarse, fibrous, granular, massive, prismatic, tabular
Formation
(1) Primary magmatic to hydrothermal, as a late-stage crystallization product in alkaline syenites.
(2) Metasomatic-hydrothermal, resulting from the interaction of lithium- and boron-bearing fluid phases with manganese-rich, altered metasediments
Paragenesis
Twinning
Rarity
Rarely
Synonyms
Sugilite
Composition
Elements
Mass
SiO₂
71.38
TiO₂
0.51
Al₂O₃
2.97
Fe₂O₃
12.76
FeO
0.19
Li₂O
3.14
Na₂O
4.37
K₂O
3.76
H₂O
0.93
Japan (Murakami et al. 1977)
Groups and Members
Osumilite-Group