Aluminium Oxide Chromium doped
Al2O3:Cr
|
Chemical name
Aluminium Oxide Chromium doped |
|
Mineral name
Sapphire (Corundum) / Rubin |
|
Chemical formula
Al2O3:Cr |
|
Melting point [°C]
ca. 2072 |
|
Crystal system
trigonal |
|
Crystal Class
ditrigonal-scalenohedral (-3 2/m) |
|
Space Group
R-3c |
|
Unit cell
a [Å]:4.74 b [Å]:4.74 c [Å]:12.97 |
|
Molecular weight [g/mol]
ca. 101.960 |
|
Formula units
Z=6 |
|
Twinning
polysynthetic twins common |
|
Mohs hardness
9 |
|
Density [g/cm3]
3.9 - 4.1 |
|
Cleavage
none |
|
Fracture / Tenacity
brittle, uneven to conchoidal |
|
Color
pink to red |
|
Streak
white |
|
Transparency
transparent, translucent to opaque |
|
Luster
adamantine to vitreous |
|
Optical character
uniaxial (-) |
|
Refractive Index
nω=1.769; nε=1.761 |
|
Birefringence δ
0.009 |
|
Pleochroism δ
distinct |
|
Other
luminescent (rare but very strong) |
|
Solubility in water
insoluble |
