Solid phase
- Official name
- mercury(II) sulfide alpha
- Secondary names
- Cinnabar; alpha-HgS; mercury sulfide; mercury sulphide; vermilion; red Cinnabar
- CAS number
- 19122-79-3
- Family
- covalent network solid
- Class
- tridimentional covalent network solid
- Compound type
- non-oxide ceramic
- Formula
- $\alpha-HgS$
- Chemical formula
- HgS
- Elemental formula
- Hg S
- Isotope mixture type
- terrestrial abundance
- Class
- tridimensional covalent networks (11)
- Type
- metal homonuclear tridimensional networks (elemental) (11.02)
- Equivalent mineral
- Cinnabar
- Phase name
- $\alpha-HgS$
- Phase type
- crystalline
- Crystal system
- trigonal
- Crystal class
- trapezohedral
- Crystal class symbol
- 32 (D3)
- Crystal spacegroup
- P3(1)21
- Comments
- There are three $HgS$ crystalline phases: $\alpha-HgS$, $\beta-HgS$, $\gamma-HgS$ and an amorphous one $\alpha'-HgS$
- Molar mass
- 232.66 $g/mol$
- Density
- 8.10 $g/cm^3$
- State NTP
- solid
- Phase transitions
-
Phase transition type Other phases Temperature - Pressure solid-solid $\beta-HgS$ 617K (344°C) at 1 bar
- Refringence type
- uniaxial
- Refringence sign
- positive
- Birefringence
- 0.351
- Refraction index $n_{\alpha}$
- 2.905
- Refraction index $n_{\beta}$
- 3.256
- Pure color
- vermilion
- Diaphaneity
- transparent to translucent
- Luster
- adamantine