Metacinnabar

Formula : HgS

Family: 
Sulfides
Space group: 
Isometric - Hextetrahedral H-M Symbol (4 3m) Space Group: F43m
Dana class: 
2.8.2.3 (2) Sulfides - Including Selenides and Tellurides (2.8) where Am Bn Xp, with (m+n):p=1:1(2.8.2) Sphalerite Group (Isometric: F43m)
High temperature: 
Metacinnabar is stable above about 330C in the pure HgS system.
Geological context: 
Found with cinnabar in mercury deposits formed in near-surface, under low-temperature conditions.

Dernière mise à jour le 25.01.2021

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
 V°
cm3·mol-1
 ΔGºf
J·mol-1
 ΔHºf
J·mol-1
 Sº
J·mol-1·k-1
 CP
J·mol-1·K-1
232.656 30.169 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp. -43668 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp. -49409 (Ref.: Internal calculation) 88.701 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp. 48.54 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp.
CP(T) = a + b·T + ·c·T-2 (T in Kelvin)
a
J·mol-1·K-1
 b * 103
J·mol-1·K-2
 c * 10-5
J·K·mol-1
 Maier Kelley Ref.
44.02 15.19 0.00 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp.
Reaction properties

Metacinnabar + 0.375H2O ⇌ 0.5Hg2+2 + 0.75HS- + 0.125S2O3-2

298.15 K, 1 bar log10K: -26.85 ΔH°r:146269 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K -29.23 -26.85 -24.20 -21.86 -19.68 -18.08 -16.96 -16.27
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-741.046578 -0.119714 32780.790198 269.558958 -2405792.967069