Constituent
Name
Tridymite
Class
silicate mineral
Compound type
tektosilicate
Relevance
main - major
Arrangement
single phase
Abundance comments
Probable traces
Formula
$Si_O2$
Chemical formula
SiO2
Elemental formula
Si O2
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Si$ Silicon element 1 constituent element main
$O$ Oxygen element 2 constituent element main
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.10

Dana

Major class
silicates (VIII)
Class
tectosilicate Si tetrahedral frameworks (75)
Type
SiO2 with [4] coordinated Si (75.01)
Group
-Tridymite- group (75.01.02)
Code
75.01.02.01
Phase type
crystalline
Crystal system
triclinic
Crystal class
pedial
Crystal class symbol
1 (C1)
Molar mass
60.08 $g/mol$
Density
2.28 - 2.33 (calc.: 2.35) $g/cm^3$
Refringence type
biaxial
Refringence sign
positive
Birefringence
0.003 - 0.006
Refraction index $n_{\alpha}$
1.471 - 1.482
Refraction index $n_{\beta}$
1.472 - 1.483
Refraction index $n_{\gamma}$
1.474 - 1.488
Dispersion V
none
Color
colorless, white, yellowish white, gray
Diaphaneity
transparent to translucent
Luster
vitreous