Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Mg$	Magnesium	element	2		constituent element	main
	$Al$	Aluminium	element	2		constituent element	main
	$Si$	Silicon	element	1		constituent element	main
	$O$	Oxygen	element	9		constituent element	main
	$H$	Hydrogen	element	4		constituent element	main

Composition comments

Common impurities: Fe Mn

Chemical functions

	Function	Number
	$(OH)^-$	4

Chemical bonds

	Bond	Number
	$O^--H$	1

Oxides

Formula	$MgO$	$Al_{2}O_{3}$	$SiO_{2}$	$H_{2}O$
Mass fraction (%)	28.92	36.59	21.56	12.93

Strunz

Class

silicates (09)

Division

phyllosilicate (09.E)

Family

with kaolinite layers composed of tetrahedral and octahedral nets (09.ED)

Code

09.ED.15

Dana

Major class

silicates (VIII)

Class

phyllosilicate sheets of six-membered rings (71)

Type

with 1:1 layers (71.01)

Group

Serpentine group (Amesite subgroup) (71.01.02c)

Code

71.01.02c.01

Phase type

crystalline

Crystal system

triclinic

Crystal class

pedial

Crystal class symbol

1 (C1)

Crystal spacegroup

P1

Refringence type

biaxial

Refringence sign

positive

Birefringence

0.015 - 0.018

Refraction index $n_{\alpha}$

1.597

Refraction index $n_{\beta}$

1.597

Refraction index $n_{\gamma}$

1.612

Dispersion V

r < v weak

Pure color

white

Color

white, light green, pale green

Diaphaneity

transparent to translucent

Luster

pearly

Links

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