Forsterite

Formula : Mg2SiO4

Space group: 
Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pbnm
Dana class: 
51.3.1.2 (51) Nesosilicate Insular SiO4 Groups Only (51.3) with all cations in octahedral [6] coordination (51.3.1)Olivine group
High temperature: 
Medium to high temperature mineral, 650C C is a temperature estimated from a deposit.
Geological context: 
mafic and ultramafic rocks, high-grade metamorphic dolomitic marbles

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
140.693 43.790 (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. -2056704 (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. -2175746 (Ref.: Internal calculation) 95.186 (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. 117.89 (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.
149.83 27.36 -35.65 (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

Forsterite + 4H+ ⇌ 2Mg+2 + H4SiO4

298.15 K, 1 bar log10K: 28.61 ΔH°r:-217115 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K 32.06 28.61 24.60 20.95 17.38 14.53 12.15 10.03
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-1098.376618 -0.153857 73215.029991 391.599004 -3706160.894881