Spodumene

Category: Silicate mineral, pyroxene

 

Chemical formula: lithium aluminium silicate, LiAl(SiO3)2

 

Crystal symmetry: Monoclinic 2/m

 

Unit cell: a = 9.46 Å, b = 8.39 Å, c = 5.22 Å; β = 110.17°; Z = 4

 

Mohs scale hardness: 6.5 - 7

 

Specific gravity: 3.03-3.23

 

Optical properties: Biaxial (+)

 

Refractive index: nα = 1.648 - 1.661 nβ = 1.655 - 1.670 nγ = 1.662 - 1.679

 

Birefringence: δ = 0.014 - 0.018

 

 

Done