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Mineral speciesFormula
 Corundum(gamma)Al2O3 
Mineralogy
Family: Hematite Group 
Space group: Trigonal - Hexagonal Scalenohedral HM symbol (-3 2/m) Space Group: R 3c 
Dana class: 4.3.1.1 
Geological context
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) 
Thermodynamics
Individual properties
Molar weight: 101.961 g/mol  ΔGºf-1,563,869 J/mol ref.  Sº: 52.30 J/mol/K ref. 
  ΔHºf-1,656,900 J/mol ref.  Cp: 82.77 J/mol/K ref. 
Reaction properties
Chemical reaction:  Corundum(gamma) + 6H+ = 2Al+3 + 3H2O 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -9.49996589e+2   -1.58416631e-1   6.18701479e+4   3.39694978e+2   -2.60598069e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)21.52
ΔH°r-277,390 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  25.94   21.52   16.39   11.64   6.83   2.85   -0.62   -3.81 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:102.98 J/mol/K 
b:37.76 J/mol/K2 
c:-27.98 J.K/mol 

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