Class

silicate mineral

Compound type

phyllosilicate

Chemical functions

	Function	Number
	$(OH)^-$	2

Chemical bonds

	Bond	Number
	$O^--H$	1

Oxides

Formula	$K_{2}O$	$Al_{2}O_{3}$	$SiO_{2}$	$H_{2}O$
Mass fraction (%)	11.82	38.4	45.26	4.52

Strunz

Class

silicates (09)

Division

phyllosilicate (09.E)

Family

with mica sheets, composed of tetrahedral and octahedral nets (09.EC)

Code

09.EC.15

Dana

Major class

silicates (VIII)

Class

phyllosilicate sheets of six-membered rings (71)

Type

with 2:1 layers (71.02)

Group

Mica group (Muscovite subgroup) (71.02.02a)

Code

71.02.02a.01

Phase type

crystalline

Crystal system

monoclinic

Crystal class

prismatic

Crystal class symbol

2/m (C2h)

Crystal spacegroup

C2/m

Molar mass

398.71 $g/mol$

Density

2.77-2.88 $g/cm^3$

Refringence type

biaxial

Refringence sign

negative

Birefringence

0.034-0.042

Refraction index $n_{\alpha}$

1.552-1.574

Refraction index $n_{\beta}$

1.582-1.61

Refraction index $n_{\gamma}$

1.586-1.616

Color

White, Gray, Silver white, Brownish white, Greenish white

Diaphaneity

transparent to translucent

Luster

vitreous