Mineral - Beryllonite
Beryllonite
Chemical Properties
Mineral Class
Phosphates
Toxicity
none
Formula
NaBe[PO₄]
Unit Cell
a=8.18 b=7.82 c=14.11 β=90° Z=12
Physical Properties
Hardness
5.5 - 6
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after {010}, distinct after {100}, indistinct after {101}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
colorless
Birefringence
0.009
Luster
Vitreous,
Adamantine
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
blocky, prismatic, tabular
Formation
Secondary, due to late magmatic, hydrothermal alteration of primary phosphates in granitic and alkaline pegmatites
Paragenesis
Twinning
Contact- and penetration-twins after {101}, pseudohexagonal twins after {110} and {100}
Rarity
Rarely
Synonyms
Beryllonite
Composition
Elements
Mass
P₂O₅
55.86
BeO
19.84
Na₂O
23.64
Maine (Palache at al. 1952)