Cinnabar(alpha)

Formula : HgS

Family: 
Sulfides
Space group: 
Trigonal - Trapezohedral H-M Symbol (3 2) Space Group: P 3121,P 3221
Dana class: 
2.8.14.1 (2)Sulfides - Including Selenides and Tellurides (2.8)where Am Bn Xp, with (m+n):p=1:1 (2.8.14) Dana Group
High temperature: 
At 25C cinnabar is a metastable mineral, a gentle desulphuration can release drops of mercury.
Geological context: 
Low temperature hydrothermal solutions in veins. Oxidized mercury deposits, supergene environment.

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 28.416 (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. -45734 (Ref.: Internal calculation) -53346 (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. 82.425 (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. 48.41 (Ref.: 87pan/mah) Pankratz L. B., 1987, A. D. Mah, and S. W. Watson, Thermodynamic Properties of Sulfides (U. S. Bureau of Mines Bulletin 689, 1987, 427 p).
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.
46.22 15.52 -2.17 (Ref.: 87pan/mah) Pankratz L. B., 1987, A. D. Mah, and S. W. Watson, Thermodynamic Properties of Sulfides (U. S. Bureau of Mines Bulletin 689, 1987, 427 p).
Reaction properties

Cinnabar(alpha) + H+ ⇌ HS- + Hg+2

298.15 K, 1 bar log10K: -39.01 ΔH°r:207256 J·mol-1 (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.
T(°C) 0 25 60 100 150 200 250 300
log10K -42.36 -39.01 -35.23 -31.85 -28.63 -26.22 -24.45 -23.27
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-915.087057 -0.145841 38659.746598 332.365384 -2890630.487667