Rhodochrosite

Formula : MnCO3

Family: 
Carbonates
Space group: 
Trigonal - Hexagonal Scalenohedral H-M Symbol (3 2/m) Space Group: R 3c
Dana class: 
14.1.1.4 (14) Anhydrous Carbonates (14.1)with Simple Formula A+ CO3 (14.1.1)Calcite Group (Trigonal: R3c)
High temperature: 
Rhodocrossite may be stable from the surface temperature to about 500C that corresponds to the formation temperature of the skarn.
Geological context: 
Commonly forms during oxidation of Mn-bearing ores in a carbonate environment and also associated with epithermal ores and skarn.

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
114.947 31.075 (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. -816068 (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. -889258 (Ref.: Internal calculation) 99.998 (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. 81.53 (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.
92.01 38.91 -19.62 (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

Rhodochrosite + H+ ⇌ HCO3- + Mn+2

298.15 K, 1 bar log10K: 0.23 ΔH°r:-22001 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K 0.55 0.23 -0.21 -0.69 -1.27 -1.88 -2.56 -3.41
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-894.480891 -0.144754 49047.875277 325.173418 -2778635.854058