Artinite

Formula : Mg2(OH)2(CO3):3H2O

Family: 
Carbonates
Space group: 
Monoclinic Space Group: C 2 or C 2/m
Dana class: 
16b.3.1.1 (16b) Carbonates - Hydroxyl or Halogen (16b.3) where Am Bn (XO3)p Zq . x(H2O), (m+n):p = 2:1(16b.3.1)Dana Group
High temperature: 
Low temperature mineral also possible in weathered environments.
Geological context: 
It is always associated with ultra-basic igneous and metamorphic rocks such as serpentinite.

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
196.679 96.900 (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. -2568352 (Ref.: Internal calculation) -2920612 (Ref.: 73hem/rob) Hemingway B. S. and Robie R. A., 1973. A calorimetric determination of the standard enthalpies of formation of huntite, CaMg3(CO3)4, and artinite, Mg2(OH)2CO3 z 3 H2O, and their standard Gibbs free energies of formation. J. Res. U.S. Geol. Survey, 1, pp. 535-541. 232.923 (Ref.: 72hem/rob) Hemingway B.S. and Robie R.A., 1972. The heat capacities at low temperatures and entropies at 298.15 K of huntite, CaMg3(CO3)4, and artinite, Mg2(OH)2CO3 z 3 H2O. Am. Mineral., 57, pp. 1754-1767. 296.05 (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.
296.52 115.73 -31.09 (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

Artinite + 3H+ ⇌ HCO3- + 2Mg+2 + 5H2O

298.15 K, 1 bar log10K: 20.14 ΔH°r:-132468 J·mol-1 (Ref.: 73hem/rob) Hemingway B. S. and Robie R. A., 1973. A calorimetric determination of the standard enthalpies of formation of huntite, CaMg3(CO3)4, and artinite, Mg2(OH)2CO3 z 3 H2O, and their standard Gibbs free energies of formation. J. Res. U.S. Geol. Survey, 1, pp. 535-541.
T(°C) 0 25 60 100 150 200 250 300
log10K 22.26 20.14 17.71 15.52 13.34 11.55 9.94 8.30
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-1292.063068 -0.198653 75563.610587 469.124860 -3807010.115900