Mineral - Villiaumite
Villiaumite
Chemical Properties
Mineral Class
Halides
Toxicity
high
Formula
NaF
Unit Cell
a=4.63 Z=4
Physical Properties
Hardness
2 - 2.5
Streak
whitered
Density
Normal (2-3,5)
Cleavage
Perfect after {001}
Fracture
smooth
Tenacity
Brittle
Optical Properties
Color
redorange
Birefringence
Luster
Vitreous
Transparency
Pleochroism
Geomineralogical Properties
Crystal System
isometric
Point Group
hexoctahedral - 4/m 3 2/m
Space Group
Fd 3 m (227)
Habit
granular, massive, Cube
Formation
Primary magmatic, forming as a late-stage crystallization product in agpaitic, highly alkaline nepheline syenites and their pegmatites under conditions of extreme fluoride enrichment and low silicic acid activity.
Paragenesis
Twinning
Rarity
Rarely
Synonyms
Villiaumite
Composition
Elements
Mass
Na
53.40
K
0.01
Mg
0.01
Ca
1.20
ZrO₂
1.50
F
44.20
Guinea (Palache et al. 1952)
Groups and Members
Halite-Group