Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Al$	Aluminium	element	4.33		constituent element	main
	$Si$	Silicon	element	3		constituent element	main
	$O$	Oxygen	element	18		constituent element	main
	$H$	Hydrogen	element	8		constituent element	main

Chemical functions

	Function	Number
	$(OH)^-$	8

Chemical bonds

	Bond	Number
	$O^--H$	1

Oxides

Formula	$Al_{2}O_{3}$	$SiO_{2}$	$H_{2}O$
Mass fraction (%)	51.87	34.39	13.75

Strunz

Class

silicates (09)

Division

phyllosilicate (09.E)

Family

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

Code

09.EC.55

Dana

Major class

silicates (VIII)

Class

phyllosilicate sheets of six-membered rings (71)

Type

interlayered 1:1, 2:1, and octahedra (71.04)

Group

Chlorite group (Tri-Dioctahedral) (71.04.01)

Code

71.04.01.01

Phase type

crystalline

Crystal system

monoclinic

Crystal class

prismatic

Crystal class symbol

2/m (C2h)

Crystal spacegroup

C2/m

Refringence type

biaxial

Refringence sign

positive

Birefringence

0.0120-0.0180

Refraction index $n_{\alpha}$

1.56-1.578

Refraction index $n_{\beta}$

1.566-1.582

Refraction index $n_{\gamma}$

1.572-1.596

Dispersion V

Dispersion r > v

Pure color

white

Color

White, Greenish white, Yellowish white

Luster

pearly

Links

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