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Mineral speciesFormula
 EpsomiteMgSO4:7H2O 
Mineralogy
Family: Miscellaneous salts 
Space group: Orthorhombic - Disphenoidal HM symbol (2 2 2) Space Group: P 212121 
Dana class: 29.6.11.1VI- 29 Hydrated Acid and Sulfates ; 29.6 Hydrated Acid and Sulfates where A XO4 . x(H2O) ; 29.6.11 
Geological context
Geological context: As efflorescences on the walls of mines, caves, and outcrops of sulfide-bearing magnesian rocks; a product of evaporation at mineral springs and saline lakes; a hydration product of kieserite and langbeinite; rarely a fumarolic sublimate. 
Thermodynamics
Individual properties
Molar weight: 246.476 g/mol  ΔGºf-2,870,093 J/mol ref.  Sº: 370.28 J/mol/K ref. 
  ΔHºf-3,388,140 J/mol ref.  Cp: 372.79 J/mol/K ref. 
Reaction properties
Chemical reaction:  Epsomite = Mg+2 + SO4-2 + 7H2O 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -1.69881588e+3   -2.57219360e-1   9.27132273e+4   6.15775302e+2   -5.42468472e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)-1.87
ΔH°r10,990 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  -2.08   -1.87   -1.70   -1.57   -1.52   -1.60   -1.89   -2.52 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:372.79 J/mol/K 
b:0.00 J/mol/K2 
c:0.00 J.K/mol 

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