Mineral - Leucite
Leucite
Chemical Properties
Mineral Class
Silicates
Toxicity
none
Formula
K[AlSi₂O₆]
Unit Cell
a=13.06 c=13.75 Z=16
Physical Properties
Hardness
5.5 - 6
Streak
white
Density
Normal (2-3,5)
Cleavage
Indistinct after {110}
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
whitegrayredcolorless
Birefringence
0.001
Luster
Vitreous
Transparency
translucent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
tetragonal
Point Group
tetragonal-dipyramidal - 4/m
Space Group
I4 1 /a (88)
Habit
massive
Formation
Magmatic, formed by crystallization from silicate melts with low SiO₂ content (silica-undersaturated) and high K₂O content, typically in effusive alkaline rocks such as phonolites or leucitites.
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Leucite
Composition
Elements
Mass
SiO₂
54.60
TiO₂
0.03
Al₂O₃
21.97
Fe₂O₃
0.89
FeO
0.14
CaO
0.10
Na₂O
0.23
K₂O
21.45
Italien (Dana 1895)
Groups and Members
Zeolite-Group
ANA-Zeolite-Subgroup