Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Mg$	Magnesium	element	0 - 1		constituent element	main
	$Fe^{2+}$	Iron(II) cation	element	1 - 2		constituent element	main
	$Fe^{3+}$	Iron(III) cation	element	0 - 1		constituent element	main
	$Al$	Aluminium	element	0 - 2		constituent element	main
	$Si$	Silicon	element	1 - 2		constituent element	main
	$O$	Oxygen	element	9		constituent element	main
	$H$	Hydrogen	element	4		constituent element	main

Composition comments

Common impurities: Ti, Ca, Mn

Chemical functions

	Function	Number
	$(OH)^-$	4

Chemical bonds

	Bond	Number
	$O^--H$	1

Oxides

Formula	$MgO$	$Al_{2}O_{3}$	$FeO$	$Fe_{2}O_{3}$	$SiO_{2}$	$H_{2}O$
Mass fraction (%)	2.44	29.28	32.58	4.83	19.98	10.89

Oxides comments

$(Fe^{2+}_{1.5},Fe^{3+}_{0.2},Al,Mg_{0.2})(Si_{1.1},Al_{0.9}O_5)(OH)_4$

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.02

Phase type

crystalline

Crystal system

monoclinic

Crystal class

domatic

Crystal class symbol

m (Cs)

Crystal spacegroup

Cm

Refringence type

biaxial

Refringence sign

unknown

Birefringence

0.030

Refraction index $n_{\alpha}$

1.620

Refraction index $n_{\gamma}$

1.650

Dispersion V

r < v strong

Pure color

green

Color

green yellow, brown green, dark green

Diaphaneity

transparent to translucent

Luster

pearly

Links

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