orthorhombic
Alexandrite
BeAl2O4:Cr
Quick Facts
Hardness
8.5
Specific Gravity
3.71
Refractive Index
1.746
Crystal Structure
orthorhombic[mmm]:{110}@1.0 + {010}@0.6 + {111}@0.4 orthorhombic
mmm
{110} {010} {111}
Physical Properties
Crystal Systemorthorhombic
Hardness (Mohs)8.5
Specific Gravity3.71
CleavageGood in one direction
FractureConchoidal to uneven
LustreVitreous
Optical Properties
Refractive Index1.746
Birefringence0.008-0.010
PleochroismStrong trichroic (green, orange, purple-red)
Dispersion0.015
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