Berndtite

Formula : SnS2

Family: 
Sulfides
Space group: 
Trigonal - Hexagonal Scalenohedral H-M Symbol (3 2/m) Space Group: P 3m1
Dana class: 
2.12.14.5 (2)Sulfides - Including Selenides and Tellurides (2.12)where Am Bn Xp, with (m+n):p=1:2 (2.12.14)Melonite Group (Trigonal: P3m1) AX2 type
High temperature: 
Hydrothermal and supergene.
Geological context: 
Secondary mineralin hydrothermally altered in tin sulfide veins and in a high temperature deposit, also described in oxidation zone of mineralized bodies

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
182.842 40.960 (Ref.: 85jac/hel) Jackson, K.J., and Helgeson, H.C., 1985, Chemical and thermodynamic constraints on the hydrothermal transport and deposition of tin: II. Interpretation of phase relations in the Southeast Asian tin belt: Econ. Geol., v. 80, no. 5, pp. 1365-1378. -145394 (Ref.: 85jac/hel) Jackson, K.J., and Helgeson, H.C., 1985, Chemical and thermodynamic constraints on the hydrothermal transport and deposition of tin: II. Interpretation of phase relations in the Southeast Asian tin belt: Econ. Geol., v. 80, no. 5, pp. 1365-1378. -153695 (Ref.: Internal calculation) 87.446 (Ref.: 85jac/hel) Jackson, K.J., and Helgeson, H.C., 1985, Chemical and thermodynamic constraints on the hydrothermal transport and deposition of tin: II. Interpretation of phase relations in the Southeast Asian tin belt: Econ. Geol., v. 80, no. 5, pp. 1365-1378. 70.13 (Ref.: 85jac/hel) Jackson, K.J., and Helgeson, H.C., 1985, Chemical and thermodynamic constraints on the hydrothermal transport and deposition of tin: II. Interpretation of phase relations in the Southeast Asian tin belt: Econ. Geol., v. 80, no. 5, pp. 1365-1378.
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.
64.89 17.57 0.00 (Ref.: 85jac/hel) Jackson, K.J., and Helgeson, H.C., 1985, Chemical and thermodynamic constraints on the hydrothermal transport and deposition of tin: II. Interpretation of phase relations in the Southeast Asian tin belt: Econ. Geol., v. 80, no. 5, pp. 1365-1378.
Reaction properties

Berndtite + 0.75H2O ⇌ 1.5HS- + Sn+2 + 0.25S2O3-2

298.15 K, 1 bar log10K: -32.15 ΔH°r:171770 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K -34.99 -32.15 -29.10 -26.52 -24.26 -22.78 -21.95 -21.78
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-1567.357747 -0.252970 77602.811799 569.623680 -5257872.302001