Mineral phase
- IMA name
- Coesite
- Class
- silicate mineral
- Compound type
- tektosilicate
- Formula
- $SiO_2$
- Chemical formula
- SiO2
- Elemental formula
- Si O2
- Isotope mixture type
- terrestrial abundance
- 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.35
Dana
- Major class
- silicates (VIII)
- Class
- tectosilicate Si tetrahedral frameworks (75)
- Type
- SiO2 with [4] coordinated Si (75.01)
- Group
- -Coesite- group (75.01.04)
- Code
- 75.01.04.01
- Phase type
- crystalline
- Crystal system
- monoclinic
- Crystal class
- prismatic
- Crystal class symbol
- 2/m (C2h)
- Crystal spacegroup
- C2/c
- Molar mass
- 60.08 $g/mol$
- Density
- 2.93 $g/cm^3$
- State NTP
- solid
- Phase transitions
-
Phase transition type Other phases Temperature - Pressure solid-solid Stishovite (metastable below 7.9 GPa at room T, below 11 GPa at 1400°C) metastable below 1.9 GPa at room T, below 4.2 GPa at 2200°C solid-solid alpha-Quartz below 1.9 GPa at room T, below 3.1 GPa at 1180°C solid-solid beta-Quartz below 3.1 GPa at 1180°C, below 4.4 GPa at 2200°C - Phase transitions comments
- the stable phase at NTP is $\alpha-Quartz$
- Refringence type
- biaxial
- Refringence sign
- positive
- Birefringence
- 0.0050-0.0060
- Refraction index $n_{\alpha}$
- 1.593-1.594
- Refraction index $n_{\beta}$
- 1.595
- Refraction index $n_{\gamma}$
- 1.599
- Pure color
- colorless
- Color
- colorless
- Diaphaneity
- transparent
- Luster
- vitreous