Beryllium Aluminium Silicate - Beryll
Be3Al2(SiO3)6
Chemical name
Beryllium Aluminium Silicate - Beryll
Mineral name
Beryll
Chemical formula
Be3Al2(SiO3)6
Crystal system
hexagonal
Crystal Class
dihexagonal-dipyramidal (6/m 2/m 2/m)
Space Group
P6/mcc
Unit cell
a [Å]:9.23
b [Å]:9.23
c [Å]:9.19
Molecular weight [g/mol]
537,48
Formula units
Z=2
Frequent crystal surfaces
{10-10}, {0001}, {11-20}
Twinning
rare
Mohs hardness
7.5 - 8
Density [g/cm3]
2.63 - 2.8
Cleavage
imperfect on {0001}
Fracture / Tenacity
uneven to conchoidal, brittle
Color
blue, green, yellow, rose, red, white, colorless
Streak
white
Transparency
transparent to translucent
Optical character
uniaxial (-)
Refractive Index
nω=1.564-1.595; nε=1.568-1.602
Birefringence δ
0.004 - 0.007
Pleochroism δ
weak to distinct