Class

silicate mineral

Compound type

tektosilicate

Comments

alpha-Quartz: exists with 2 chiral space groups: P3(2)21 and P3(1)21

Composition comments

Common impurities: traces of Al,Fe,Ti,Li,Ca,Mg, etc

Chemical bonds

	Bond	Number
	$\geq Si-O-$	4

Oxides

Formula	$SiO_{2}$
Mass fraction (%)	100.0

Strunz

Class

oxides - hydroxides - arsenites (04)

Division

metal:oxygen = 1:2 and similar (04.D)

Family

with small cations: Silica family (04.DA)

Code

04.DA.05

Dana

Major class

silicates (VIII)

Class

tectosilicate Si tetrahedral frameworks (75)

Type

SiO2 with [4] coordinated Si (75.01)

Group

Quartz group (75.01.03)

Code

75.01.03.01

Phase type

crystalline

Crystal system

trigonal

Crystal class

trapezohedral

Crystal class symbol

32 (D3)

Crystal spacegroup

P3(2)21

Composition order

ordered

Comments

Quartz forms left- and right-handed crystals. Space groups: $P3_121$ (right) and $P3_221$ (left)

Molar mass

60.08 $g/mol$

Density

2.60 - 2.65 $g/cm^3$

Refringence type

uniaxial

Refringence sign

positive

Birefringence

0.009

Refraction index $n_{\alpha}$

1.543 - 1.545

Refraction index $n_{\beta}$

1.552 - 1.554

Color

colorless, brown, violet, gray, yellow

Diaphaneity

transparent

Luster

vitreous