Aluminium Hydroxide
Al(OH)3
Chemical name
Aluminium Hydroxide
Mineral name
Gibbsite
Chemical formula
Al(OH)3
Crystal system
monoclinic
Crystal Class
monoclinic-prismatic (2/m)
Space Group
P2_1/m
Unit cell
a [Å]:8.64
b [Å]:5.07
c [Å]:9.72
Formula units
Z=8
Frequent crystal surfaces
{001}, {101}, {110}
Twinning
on {001}, rare on {100}, {110}
Mohs hardness
2.5 - 3.5
Density [g/cm3]
2.3 - 2.4
Cleavage
perfect on (001)
Fracture / Tenacity
uneven
Color
colorless, white, gray, green, blue
Streak
white
Transparency
transparent to translucent
Optical character
biaxial (+)
Refractive Index
nα=1.568-1.570; nβ=1.568-1.570; nΥ=1.586-1.587
Birefringence δ
0.018