Mineral - Berborite
Berborite
Chemical Properties
Mineral Class
Borates
Toxicity
none
Formula
Be₂(BO₃)(OH,F) · H₂O
Unit Cell
a=4.43 c=5.34-10.65 Z=1-2
Physical Properties
Hardness
3
Streak
white
Density
Normal (2-3,5)
Cleavage
Perfect after {001}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
colorless
Birefringence
0.095
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
trigonal , hexagonal
Point Group
trigonal-pyramidal - 3 , ditrigonal-pyramidal - 3m , hexagonal-pyramidal - 6
Space Group
P3 (143) , P3c1 (158) , P6 3 (173)
Habit
dipyramidal
Formation
In contact metamorphic skarns and serpentinized dolostone
Paragenesis
Twinning
Rarity
Very rare
Synonyms
Berborite
Composition
Elements
Mass
B₂O₃
23.50
BeO
39.30
H₂O
[33.20]
Russia (Nefedov 1967)