Chalcocite(alpha)

Formula : Cu2S

Family: 
Sulfides
Space group: 
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 21/c
Dana class: 
2.4.7.1 (2) Sulfides - Including Selenides and Tellurides (2.4) where Am Bn Xp, with (m+n):p=2:1(2.4.7) Chalcocite Group ([Cu]2-x S] formulae)
High temperature: 
Chalcocite is stable under a normal atmospheric conditions.
Geological context: 
Secondary mineral in or near the oxidized zone of copper sulfide 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
159.158 28.420 (Ref.: 84pan/stu) L.B. Pankratz, J.M. Stuve, and N.A. Gokcen, 'Thermodynamic Data for Mineral Technology,' Bulletin 677, U.S. Bureau of Mines (1984). -84205 (Ref.: 00pui) Puigdomenech, I., 2000. Thermodynamic data for copper: implications for the corrosion of copper under repository conditions, SKB report. SKB/Swedish Nuclear Fuel and Waste Management, p. 96. -78884 (Ref.: Internal calculation) 116.200 (Ref.: 95rob/hem) Robie R.A., and Hemingway B.S., 1995. Thermodynamic properties of minerals and related substances at 298.15 K and 1 Bar (105 Pascals) pressure and at higher temperatures. U.S. Geol. Survey Bull., 2131, 461 pp. 76.32 (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.
52.84 78.74 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

Chalcocite(alpha) + H+ ⇌ 2Cu+ + HS-

298.15 K, 1 bar log10K: -34.02 ΔH°r:203728 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K -37.30 -34.02 -30.28 -26.90 -23.62 -21.13 -19.25 -17.93
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-867.994651 -0.136448 36090.717551 316.645760 -2658935.466087