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Mineral speciesFormula
 FoshagiteCa4Si3O9(OH)2:0.5H2O 
Mineralogy
Family: Inosilicates, Wollastonite-2M - Foshagite series 
Space group: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 21/m 
Dana class: 65.2.2.1 (65) Inosilicate Single-Width Unbranched Chains, W=1(65.2) with chains P=3 (65.2.2) Dana Group 
Geological context
High temperature: High temperature mineral but.. 
Geological context: Metamorphosed limestone. 
Thermodynamics
Individual properties
Molar weight: 431.585 g/mol  ΔGºf-5,643,832 J/mol ref.  Sº: 295.07 J/mol/K ref. 
  ΔHºf-6,032,430 J/mol ref.  Cp: 309.38 J/mol/K ref. 
Reaction properties
Chemical reaction:  Foshagite + 8H+ + 0.5H2O = 4Ca+2 + 3H4SiO4 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -1.09789570e+3   -1.70310221e-1   7.58512405e+4   4.01063504e+2   -2.86046758e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)65.96
ΔH°r-380,238 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  72.09   65.96   59.01   52.77   46.70   41.90   37.91   34.37 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:309.38 J/mol/K 
b:0.00 J/mol/K2 
c:0.00 J.K/mol 

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