Zinc Aluminate Zinc Aluminium Spinell
ZnAl2O4
Chemical name
Zinc Aluminate Zinc Aluminium Spinell
Mineral name
Gahnite
Chemical formula
ZnAl2O4
Crystal system
cubic
Crystal Class
cubic-hexoctahedral (4/m -3 2/m)
Space Group
Fd-3m
Unit cell
a [Å]:8.09
b [Å]:8.09
c [Å]:8.09
Formula units
Z=8
Frequent crystal surfaces
{111}, {110}, {211}, occasionally {100}
Twinning
on (111)
Mohs hardness
7.5 - 8
Density [g/cm3]
4.6
Cleavage
indistinct
Fracture / Tenacity
brittle, uneven to conchoidal
Color
blue, green, yellowish brown, greenish black
Streak
gray to white
Transparency
translucent to opaque
Optical character
isotropic
Refractive Index
n=1.79-1.80
Pleochroism δ
none