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Mineral speciesFormula
 CordieriteMg2Al3(AlSi5)O18 
Mineralogy
Family: Cyclosilicates, Cordierite Group 
Space group: Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: C ccm 
Dana class: 61.2.1.1 (61) Cyclosilicate Six-Membered Rings (61.2) with Al substituted rings (61.2.1)Cordierite group 
Geological context
High temperature: The stability of cordierite is limited by pessure to give andalusite or sillimanite and phyllosilicates: stability domain range approximately between 500C to more than 700C. 
Geological context: Magmatic, metamorphic, and pegmatitic rocks. 
Thermodynamics
Individual properties
Molar weight: 584.953 g/mol  ΔGºf-8,651,139 J/mol ref.  Sº: 407.20 J/mol/K ref. 
  ΔHºf-9,161,500 J/mol ref.  Cp: 443.28 J/mol/K ref. 
Reaction properties
Chemical reaction:  Cordierite + 16H+ + 2H2O = 4Al+3 + 2Mg+2 + 5H4SiO4 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -2.78640714e+3   -4.48528052e-1   1.74999226e+5   9.97580110e+2   -7.63200961e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)49.41
ΔH°r-660,411 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  59.96   49.41   37.23   26.06   14.88   5.67   -2.37   -9.79 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:531.19 J/mol/K 
b:194.72 J/mol/K2 
c:-129.75 J.K/mol 

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