Rough Alexandrite

Chemical formula BeAl2O4:Cr3+
Density, g / cm3 3,69-3,75
Mohs Hardness 8,5
Syngony Rhombic Options of el.cells a=4.248, b=9.41, c=5.481
Refractive index 1,745-1,754
Birefringence 0,01
Pleochroism Strong
Color at daylight Greenish Blue
Color at incandescent bulbs Violet-purple
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