Constituent Plagioclase Ab86 | SSHADE

Constituent

Name: Plagioclase Ab86
IMA name: Albite-Anorthite series

Class: silicate mineral
Compound type: tektosilicate
Comments: Plagioclase is a wider series $(Na,Ca)(Si,Al)_4O_8$ of the feldspar group

Constituent abundance in material

Relevance: main - major
Arrangement: homogeneous in multi-phases
Mass fraction: 0.113 $\pm$ 0.004

Chemical composition

Formula: $(Na_{0.86},Ca_{0.14})(Al_{0.14},Si_{0.86})AlSi_2O_8$
Chemical formula: ((Na)0.86(Ca)0.14)((Al)0.14(Si)0.86)AlSi2O8
Elemental formula: Na0.86 Ca0.14 Al1.14 Si2.86 O8
Isotope mixture type: terrestrial abundance

	Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Na$	Sodium	element	0.86	1.0	constituent element	main
	$Ca$	Calcium	element	0.14	1.0	constituent element	main
	$Al$	Aluminium	element	1.14	1.0	constituent element	main
	$Si$	Silicon	element	2.86	1.0	constituent element	main
	$O$	Oxygen	element	8	1.0	constituent element	main

Composition comments: Common replacement: K (limited solid solution) - Common impurities: Ti, Fe, Mg, H2O

Oxides composition

Oxides

Formula	$Na_{2}O$	$CaO$	$K_{2}O$	$Al_{2}O_{3}$	$SiO_{2}$
Mass fraction (%)

Classifications

Strunz

Class: silicates (09)
Division: tektosilicate without zeolitic H2O (09.F)
Family: without additional non-tetrahedral anions, (Al,B):Si = 1:1 (09.FA)
Code: 09.FA.35

Dana

Major class: silicates (VIII)
Class: tectosilicate Al-Si framework (76)
Type: with Al-Si frameworks (76.01)
Group: Plagioclase series (76.01.03)

Phase type: amorphous

Crystallography

Crystal system: amorphous
Crystal class: pinacoidal
Crystal class symbol: -1 (Ci)
Crystal spacegroup: P-1

Physical properties

Molar mass: 263.02 - 277.41 $g/mol$
Density: 2.61 - 2.76 $g/cm^3$

Optical properties

Refringence type: biaxial
Refringence sign: positive or negative
Birefringence: 0.009 - 0.012
Refraction index $n_{\alpha}$: 1.528 - 1.576
Refraction index $n_{\beta}$: 1.532 - 1.583
Refraction index $n_{\gamma}$: 1.538 - 1.588
Dispersion V: weak to relatively weak
Color: white, gray, bluish white, reddish white, greenish white
Diaphaneity: transparent to subtranslucent
Luster: vitreous