Phlogopite
KMg3(AlSi3O10)(F,OH)2
|
Chemical name
Phlogopite |
|
Chemical formula
KMg3(AlSi3O10)(F,OH)2 |
|
Crystal system
monoclinic |
|
Crystal Class
monoclinic-prismatic (2/m) |
|
Space Group
C2/m |
|
Unit cell
a [Å]:3.16 b [Å]:3.16 c [Å]:12.30 |
|
Molecular weight [g/mol]
419.25 |
|
Formula units
Z=2 |
|
Frequent crystal surfaces
{001} |
|
Twinning
composition twinning |
|
Mohs hardness
2 - 2.5 |
|
Density [g/cm3]
2.75 - 2.97 |
|
Cleavage
perfect on (001) (basal) |
|
Fracture / Tenacity
tough, flexible thin laminae |
|
Color
brownish red, dark brown, yellowish brown, green, white |
|
Streak
white |
|
Transparency
transparent to translucent |
|
Luster
pearly, slightly metallic on cleavage surfaces |
|
Optical character
biaxial (-) |
|
Refractive Index
nα=1.530-1.573; nβ=1.557-1.617; nΥ=1.558-1.618 |
|
Birefringence δ
0.028-0.045 |
|
Other
fluorescent |
