Crystallography and Physical Properties
Wadsleyite crystallizes in the orthorhombic crystal system and has a unit cell volume of 550.00 ų. Its space group is Imma and its cell parameters are as follows: a = 5.6921 Å, b = 11.46 Å and c = 8.253 Å.(Price, Putnis, Agrell and Smith, 1983) A more recent structure of wadsleyite confirms the cell parameters to be a = 5.698 Å, b = 11.438 Å and c = 8.257 Å.(Horiuchi and Sawamoto, 1981). Pure magnesian wadsleyite is colorless, but iron bearing varieties are dark green.
The wadsleyite minerals generally have a microcrystalline texture and are fractured. Because of small crystal size, detailed optical data could not be obtained; however, wadsleyite is anisotropic with low first-order birefringence colors.(Price, Putnis, Agrell and Smith, 1983) It is biaxial with a mean refractive index of n = 1.76. I has a calculated specific gravity of 3.84. In X-ray powder diffraction, its strongest points in pattern are: 2.886(50)(040), 2.691(40)(013), 2.452(100,141), 2.038(80)(240), 1.442(80)(244).(Price, Putnis, Agrell and Smith, 1983)
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