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
αHgS
Chemical formula
HgS
Elemental formula
Hg S
Isotope mixture type
terrestrial abundance
4.0
  Formula Name Family Number min-max Mole fraction Isotope mole fraction State Relevance
Hg Mercury element 1 0.5 1 constituent element main
S Sulfur element 1 0.5 1 constituent element main
Class
tridimensional covalent networks (11)
Type
metal homonuclear tridimensional networks (elemental) (11.02)
Equivalent mineral
Cinnabar
Phase name
αHgS
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: αHgS, βHgS, γHgS and an amorphous one αHgS
Molar mass
232.66 g/mol
Density
8.10 g/cm3
State NTP
solid
Phase transitions
Phase transition type Other phases Temperature - Pressure
solid-solid βHgS 617K (344°C) at 1 bar
Refringence type
uniaxial
Refringence sign
positive
Birefringence
0.351
Refraction index nα
2.905
Refraction index nβ
3.256
Pure color
vermilion
Diaphaneity
transparent to translucent
Luster
adamantine