Class

silicate mineral

Compound type

tektosilicate

Comments

Albite: name by extension in the range Ca=0-10%, K=0-10% of $(Na,Ca,K)Al_2Si_2O_8$

	Formula	Name	Family	Number min-max	Isotope mole fraction	State	Relevance
	$Na$	Sodium	element	1		constituent element	main
	$Al$	Aluminium	element	1		constituent element	main
	$Si$	Silicon	element	3		constituent element	main
	$O$	Oxygen	element	8		constituent element	main

Composition comments

Typical formula: Na0.95Ca0.05Al1.05Si2.95O8 - Common replacement: Ca, K - Common impurities: Mg

Oxides

Formula	$Na_{2}O$	$CaO$	$K_{2}O$	$Al_{2}O_{3}$	$SiO_{2}$
Mass fraction (%)	12.26			20.35	67.39

Oxides comments

frequently also Na2O ~1%

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)

Code

76.01.03.01

Phase type

crystalline

Crystal system

triclinic

Crystal class

pinacoidal

Crystal class symbol

-1 (Ci)

Crystal spacegroup

P-1

Texture

polycrystalline

Molar mass

263.02 $g/mol$

Density

2.61 - 2.63 $g/cm^3$

Refringence type

biaxial

Refringence sign

positive

Birefringence

0.009 - 0.010

Refraction index $n_{\alpha}$

1.528 - 1.533

Refraction index $n_{\beta}$

1.532 - 1.537

Refraction index $n_{\gamma}$

1.538 - 1.542

Dispersion V

r < v; weak (low)

Color

white, gray, greenish gray, bluish green

Diaphaneity

transparent to subtranslucent

Luster

vitreous