Lithium Mica
K(Li,Al)3(Al,Si,Rb)4O10 (F,OH)2
Chemical name
Lithium Mica |
Mineral name
Lepidolite |
Chemical formula
K(Li,Al)3(Al,Si,Rb)4O10
(F,OH)2 |
Crystal system
monoclinic |
Crystal Class
monoclinic-prismatic (2/m) |
Space Group
C2/m |
Unit cell
a [Å]:5.21 b [Å]:8.97 c [Å]:20.16 |
Molecular weight [g/mol]
388.30 |
Formula units
Z=2 |
Twinning
rare, composition plane on {001} |
Mohs hardness
2.5 - 3 |
Density [g/cm3]
2.8 - 2.9 |
Cleavage
perfect on {001} |
Fracture / Tenacity
uneven |
Color
pink, purple, rose-red, violet-gray, yellowish, white, colorless |
Streak
white |
Transparency
transparent to translucent |
Luster
vitreous to pearly |
Optical character
biaxial (-) |
Refractive Index
nα=1.525-1.548; nβ=1.551-1.580; nΥ=1.554-1.586 |
Birefringence δ
0.029 - 0.038 |
Pleochroism δ
moderate to strong |