Mineral - Béhierite
Béhierite
Chemical Properties
Mineral Class
Borates
Toxicity
none
Formula
(Ta,Nb)(BO₄)
Unit Cell
a=6.21 c=5.47 Z=4
Physical Properties
Hardness
7 - 7.5
Streak
white
Density
Very Heavy (>6)
Cleavage
Distinct after {110} and {010}
Fracture
conchoidal
Tenacity
Optical Properties
Color
whiteblackgraypink
Birefringence
Luster
Adamantine
Transparency
translucent,
opaque
Pleochroism
Geomineralogical Properties
Crystal System
tetragonal
Point Group
ditetragonal-dipyramidal - 4/m 2/m 2/m
Space Group
I4 1 /amd (141)
Habit
dipyramidal, pyramidal, tabular
Formation
In magmatic REE-pegmatites
Paragenesis
Twinning
Rarity
Very rare
Synonyms
Béhierite, Behierite
Composition
Elements
Mass
B₂O₃
[15.77]
Nb₂O₅
21.73
Ta₂O₅
63.95
Madagascar (Mrose et al. 1961)