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Mineral speciesFormula
 GyroliteCa2Si3O7.5(OH):2H2O 
Mineralogy
Family: Cement phases Group 
Space group: Hexagonal - Pyramidal HM symbol (6) Space Group: P 61 
Dana class: 73.2.2c.1VIII- 73 Phyllosilicates Phyllosilicate Condensed Tetrahedral Sheets ; 73.2 Phyllosilicates Phyllosilicate Condensed Tetrahedral Sheets with double and single layers ; 73.2.2c Reyerite group (Gyrolite Subgroup) 
Geological context
Geological context: As replacements of wall rocks and in vugs, amygdules, and veinlets in basalts; in hydrothermally altered rhyolites and sediments; in some ore deposits. 
Thermodynamics
Individual properties
Molar weight: 337.446 g/mol  ΔGºf-4,550,063 J/mol ref.  Sº: 309.32 J/mol/K ref. 
  ΔHºf-4,917,990 J/mol ref.  Cp: 325.94 J/mol/K ref. 
Reaction properties
Chemical reaction:  Gyrolite + 4H+ + 1.5H2O = 2Ca+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
 -5.71621497e+2   -8.64344578e-2   3.55379242e+4   2.08891767e+2   -1.45371294e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)22.34
ΔH°r-122,848 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  24.33   22.34   20.12   18.17   16.32   14.88   13.69   12.60 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:325.94 J/mol/K 
b:0.00 J/mol/K2 
c:0.00 J.K/mol 

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