Material name Alexandrite
Composition BeAl2O4
Chemical formula weight 126.97
System Orthorhombic
Temperature (ºC) r.t.
a (Å), b (Å), c (Å) 9.404 5.476 4.427 @
α (deg), β (deg), γ (deg) 90 90 90 @
Unit cell volume (Å3) 228
Calculated density (g/p3) 3.70
Z 4
Space group Pnma (No.62)
atom site g x/a y/b z/c B2)
Be 4c 1 0.0929(7) 1/4 0.433(1) 0.15(6)
Al1 4a 1 0 0 0 0.07(1)
Al2 4c 1 0.2732(2) 1/4 -0.0060(3) 0.10(1)
O1 4c 1 0.0905(3) 1/4 0.7902(6) 0.06(2)
O2 4c 1 0.4334(3) 1/4 0.2410(7) 0.23(2)
O3 8d 1 0.1632(2) 0.0172(6) 0.2585(4) 0.14(1)

Reference: E.F. Farrell, J.H. Fang, and R.E. Newnham, American Mineralogist, 48, 804 (1963).