Spinel

Formula : MgAl2O4

Family: 
Oxides
Space group: 
Isometric - Hexoctahedral H-M Symbol (4/m 3 2/m) Space Group: F d3m
Dana class: 
7.2.1.1 (7) Multiple Oxides (7.2)(A+ B++)2 X4 Spinel group (7.2.1) (Aluminum subgroup)
High temperature: 
Stable around 800C to more than 1200C.
Geological context: 
Common as metamorphic mineral found in limestone and dolomite marbles and as magmatic pase in very-low silica and alkali igneous rocks (e.g. peridotites).

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
142.266 39.710 (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. -2163153 (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. -2288063 (Ref.: Internal calculation) 80.626 (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. 116.16 (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.
153.86 26.84 -40.62 (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

Spinel + 8H+ ⇌ 2Al+3 + Mg+2 + 4H2O

298.15 K, 1 bar log10K: 37.86 ΔH°r:-399057 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K 44.23 37.86 30.49 23.72 16.95 11.41 6.64 2.31
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-1357.126890 -0.218292 89808.713445 485.601424 -3799467.820617