Pyrrhotite

Formula : FeS

Family: 
Sulfides
Space group: 
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: A2/a
Dana class: 
2.8.10.1 (2) Sulfides - Including Selenides and Tellurides (2.8) where Am Bn Xp, with (m+n):p=1:1(2.8.10)Dana Group 2.8.10.1 Pyrrhotite Fe(1-x)S(x=0-0.17) A2/a 2/m
High temperature: 
Pyrrhotite can be produced at laboratory scale at around 250C by reduction with the hydrogen. In conclusion pyrrhotite needs reduced environment and it is concerned by a wide range of temperature : from roughly 100C to more than 1000C.
Geological context: 
Pyrrhotite is a widespred mineral from hyrothemal to magmatic deposits.

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
87.913 18.200 (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. -99289 (Ref.: Internal calculation) -96291 (Ref.: 05wal/pel) Waldner, P., Pelton, A.D. (2005) Thermodynamic modeling of the Fe-S system. Journal of Phase Equilibria and Diffusion 26, 23-38. 69.429 (Ref.: 05wal/pel) Waldner, P., Pelton, A.D. (2005) Thermodynamic modeling of the Fe-S system. Journal of Phase Equilibria and Diffusion 26, 23-38. 50.50 (Ref.: 05wal/pel) Waldner, P., Pelton, A.D. (2005) Thermodynamic modeling of the Fe-S system. Journal of Phase Equilibria and Diffusion 26, 23-38.
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.
-472.97 1091.66 176.00 (Ref.: 05wal/pel) Waldner, P., Pelton, A.D. (2005) Thermodynamic modeling of the Fe-S system. Journal of Phase Equilibria and Diffusion 26, 23-38.
Reaction properties

Pyrrhotite + H+ ⇌ Fe+2 + HS-

298.15 K, 1 bar log10K: -3.68 ΔH°r:-10009 J·mol-1 (Ref.: 05wal/pel) Waldner, P., Pelton, A.D. (2005) Thermodynamic modeling of the Fe-S system. Journal of Phase Equilibria and Diffusion 26, 23-38.
T(°C) 0 25 60 100 150 200 250 300
log10K -3.56 -3.68 -3.91 -4.22 -4.66 -5.19 -5.86 -6.77
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-1132.182340 -0.182358 61304.820889 411.036283 -3540353.653024