Muscovite

Al_2.88Fe_0.12KO₁₂Si₃

Birle, J.Tettenhorst, R.

Mineralogical Magazine (1968) 36, 883-886

a=5.194Å   b=8.996Å   c=20.09599Å

α=90°   β=95.18°   γ=90°