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Mineral speciesFormula
 ClaudetiteAs2O3 
Mineralogy
Family: Claudetite - Valentinite series 
Space group: Monoclinic - Prismatic HM symbol (2/m) Space Group: P 21/n 
Dana class: 4.3.10.1III - 4 Oxide Minerals ; 4.3 Simple Oxides with a cation charge of 3+ (A+++2 O3) ; 4.3.10 
Geological context
Geological context: A secondary oxidation product derived from realgar, arsenopyrite, or other arsenic-bearing minerals. Also produced as a sublimate during mine fires. 
Thermodynamics
Individual properties
Molar weight: 197.841 g/mol  ΔGºf-576,262 J/mol ref.  Sº: 113.35 J/mol/K ref. 
  ΔHºf-655,500 J/mol ref.  Cp: 97.04 J/mol/K ref. 
Reaction properties
Chemical reaction:  Claudetite + 3H2O = 2H2AsO3- + 2H+ 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -4.92886706e+2   -9.15035076e-2   1.73421618e+4   1.83180653e+2   -9.95275474e+5 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)-19.93
ΔH°r-294,176 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  -21.43   -19.93   -18.18   -16.58   -15.07   -13.97   -13.22   -12.84 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:99.83 J/mol/K 
b:44.94 J/mol/K2 
c:-14.39 J.K/mol 

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