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Mineral speciesFormula
 Glauconite(K0.75Mg0.25Fe1.5Al0.25)(Al0.25Si3.75)O10(OH)2 
Mineralogy
Family: Mica Group 
Geological context
Geological context: Altered from detrital biotite or other parent materials, by marine diagenesis in shallow water under reducing conditions; especially in loosely consolidated sandstone (greensand),and impure limestone and silstone. 
Thermodynamics
Individual properties
Molar weight: 431.991 g/mol  ΔGºf-4,796,224 J/mol ref.  Sº: 337.04 J/mol/K ref. 
  ΔHºf-5,156,060 J/mol ref.  Cp: 343.82 J/mol/K ref. 
Reaction properties
Chemical reaction:  Glauconite + 7H+ + 3H2O = 0.5Al+3 + 1.25Fe+3 + 0.75K+ + 0.25Mg+2 + 3.75H4SiO4 + 0.25Fe+2 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -1.20509898e+3   -1.84893039e-1   6.86029485e+4   4.32584149e+2   -3.35464988e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)2.53
ΔH°r-1,131 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  4.54   2.53   0.26   -1.77   -3.77   -5.41   -6.91   -8.40 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:343.82 J/mol/K 
b:0.00 J/mol/K2 
c:0.00 J.K/mol 

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