Corundum(alpha)

Formula : Al2O3

Family: 
Oxides
Space group: 
Trigonal - Hexagonal Scalenohedral H-M Symbol (3 2/m) Space Group: R 3c
Dana class: 
4.3.1.1 (4) Simple Oxides (4.3) with a cation charge of 3+ (A+++2 O3)(4.3.1) Corundum-Hematite group (Rhombohedral: R3_c)
High temperature: 
High temperature mineral, related to metamorphisme and udersaturated magmas.
Geological context: 
Contact and regionally metamorphosed rocks but also in magma with low silica content (alkaline context)

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
101.961 25.580 (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. -1582257 (Ref.: Internal calculation) -1675700 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p. 50.920 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p. 79.03 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p.
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.
98.25 36.75 -26.83 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p.
Reaction properties

Corundum(alpha) + 6H+ ⇌ 2Al+3 + 3H2O

298.15 K, 1 bar log10K: 18.30 ΔH°r:-258590 J·mol-1 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p.
T(°C) 0 25 60 100 150 200 250 300
log10K 22.42 18.30 13.51 9.08 4.60 0.87 -2.39 -5.41
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-948.600086 -0.157877 60832.418507 339.148013 -2601091.038635