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Mineral speciesFormula
 CopiapiteFe5(SO4)6(OH)2:20H2O 
Mineralogy
Space group: Triclinic Pedial or Pinacoidal HM symbol (1 or -1) Space Group: P1 
Dana class: 31.10.5.13 2/m ; 31.10 Hydrated Sulfates Containing Hydroxyl or Halogen miscellaneous ; 31.10.5 Copiapite Group 
Geological context
Geological context: A secondary mineral formed typically by the weathering and oxidation of pyrite in a wide range of rock types, preserved in arid climates; rarely associated with fumarolic action. 
Thermodynamics
Individual properties
Molar weight: 1,249.937 g/mol  ΔGºf-9,931,433 J/mol ref.  Sº: 1,444.00 J/mol/K ref. 
  ΔHºf-11,824,000 J/mol ref.   
Reaction properties
Chemical reaction:  Copiapite + 2H+ = 4Fe+3 + 6SO4-2 + Fe+2 + 22H2O 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -1.08643853e+4   -1.62485746e+0   5.99060619e+5   3.92017797e+3   -3.35315298e+7 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)-16.56
ΔH°r189,226 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  -13.35   -16.56   -20.36   -23.75   -27.17   -30.38   -34.16   -39.64 

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