Constituent Na-exchanged smectite SWa-1 size-fraction <1 µm | SSHADE

Constituent

Name: Na-exchanged smectite SWa-1 size-fraction <1 µm
IMA name: Montmorillonite

Class: silicate mineral
Compound type: phyllosilicate
Comments: Montmorillonite has a typical hydration number of 10 - Chemical composition and molecular mass are per half unit cell

Constituent abundance in material

Relevance: main - major
Arrangement: homogeneous in multi-phases
Mass fraction: 1.0 $\pm$ 0.05

Chemical composition

Formula: $Na_{0.31}(Al_{0.67}Mg_{0.07}Fe_{1.26})(Si_{3.76}Al_{0.24})O_{10}(OH)_2$
Chemical formula: (Na,Ca)0.3(Al,Mg)2Si4O10(OH)2•n(H2O)
Elemental formula: (Na)0.31-0.3 (Al)0.91-2 (Mg)0.07-2 Fe1.26 (Si)3.76-4 O12 H2
Isotope mixture type: terrestrial abundance

	Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Na$	Sodium	element	0.31 - 0.3	1.0	constituent element	main
	$Al$	Aluminium	element	0.91 - 2	1.0	constituent element	main
	$Mg$	Magnesium	element	0.07 - 2	1.0	constituent element	main
	$Fe$	Iron	element	1.26	1.0	constituent element	main
	$Si$	Silicon	element	3.76 - 4	1.0	constituent element	main
	$O$	Oxygen	element	12	1.0	constituent element	main
	$H$	Hydrogen	element	2	1.0	constituent element	main

Composition comments: Typical formula: $(Na_{0.2}Ca_{0.1})Al_2.Si_4O_{10}(OH)_2 \bullet (H_2O)_{10}$ - Common impurities: Fe, K - Intermolecular water was not taken into account in atomic composition calculation

Chemical functions and bonds

Chemical functions

	Function	Number
	$(OH)^-$	2

Chemical bonds

	Bond	Number
	$O^--H$	1

Oxides composition

Oxides

Formula	$SiO_{2}$	$Al_{2}O_{3}$	$MgO$	$Fe_{2}O_{3}$	$Na_{2}O$	$H_{2}O$
Mass fraction (%)	56.01	11.5	0.7	24.94	2.38	4.47

Classifications

Strunz

Class: silicates (09)
Division: phyllosilicate (09.E)
Family: with mica sheets, composed of tetrahedral and octahedral nets (09.EC)
Code: 09.EC.40

Dana

Major class: silicates (VIII)
Class: phyllosilicate sheets of six-membered rings (71)
Type: with 2:1 clays (71.03)
Group: Smectite group (Dioctahedral Smectites) (71.03.01a)
Code: 71.03.01a.02

Phase type: crystalline

Crystallography

Crystal system: monoclinic
Crystal class: prismatic
Crystal class symbol: 2/m (C2h)
Crystal spacegroup: C2/m

Texture: cryptocrystalline

Physical properties

Molar mass: 403.0 $g/mol$
Density: N/A $g/cm^3$

Optical properties

Refringence type: biaxial
Refringence sign: negative
Birefringence: 0.015 - 0.020
Refraction index $n_{\alpha}$: 1.485 - 1.535
Refraction index $n_{\beta}$: 1.504 - 1.550
Refraction index $n_{\gamma}$: 1.505 - 1.550
Dispersion V: 0
Color: gray white, yellow, brownish yellow, greenish yellow
Diaphaneity: translucent to opaque
Luster: N/A