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Mineral speciesFormula
 GreenaliteFe3Si2O5(OH)4 
Mineralogy
Family: Kaolinite-Serpentine Group 
Space group: Monoclinic Space Group: Unknown 
Dana class: 71.1.2b.4 (71) Phyllosilicate Sheets of Six-Membered Rings (71.1) with 1:1 layers (71.1.2b) Serpentine group (Lizardite subgroup) 
Geological context
High temperature: Literature is poor about this mineral, estimated temperature for Chamosite Greenalite Stilpnomelane Siderite Pyrite parageneses is around 300C. 
Geological context: A primary phase in some banded iron formations related to regional metamorphisme. 
Thermodynamics
Individual properties
Molar weight: 371.738 g/mol  ΔGºf-3,002,962 J/mol ref.  Sº: 304.50 J/mol/K ref. 
  ΔHºf-3,301,000 J/mol ref.  Cp: 302.32 J/mol/K ref. 
Reaction properties
Chemical reaction:  Greenalite + 6H+ = 3Fe+2 + 2H4SiO4 + H2O 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -1.03782369e+3   -1.59739844e-1   6.25129065e+4   3.75486054e+2   -2.80650058e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)21.76
ΔH°r-177,218 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  24.62   21.76   18.54   15.66   12.85   10.60   8.66   6.84 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:303.39 J/mol/K 
b:166.34 J/mol/K2 
c:-45.04 J.K/mol 

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