Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$K$	Potassium	element	1		constituent element	main
	$Al$	Aluminium	element	3		constituent element	main
	$Si$	Silicon	element	3		constituent element	main
	$O$	Oxygen	element	12		constituent element	main
	$H$	Hydrogen	element	2		constituent element	main

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

Phyllosilicates 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

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

Pure color

white

Color

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

Diaphaneity

transparent to translucent

Luster

vitreous

Links

• Wikipedia
• Webmineral database
• Mindat
• Handbook of Mineralogy (Min. Soc. Am)