Muscovite

KAl2[(0H,F) AlSi3O10]

Muscovite - KAl2[(0H,F) AlSi3O10]Muscovite - KAl2[(0H,F) AlSi3O10]
Chemical name
Muscovite
Mineral name
Muscovite
Chemical formula
KAl2[(0H,F) AlSi3O10]
Melting point [°C]
∼ 1320
Crystal system
monoclinic
Crystal Class
Prismatic (2/m)
Space Group
C62h-C2
Unit cell
a [Å]:5,19
b [Å]:9,04
c [Å]:20,08
Molecular weight [g/mol]
398.71
Formula units
Z=4
Twinning
Common on the [310], less common on the {001}
Mohs hardness
2 - 2.5, 4
Density [g/cm3]
2.77 - 2.88
Cleavage
(001) perfect
Refractive Index
nα = 1.552–1.576,
nβ = 1.582–1.615,
nγ = 1.587–1.618
Birefringence δ
0.035 - 0.042