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Mineral speciesFormula
 GypsumCaSO4:2H2O 
Mineralogy
Family: Bassanite - Ardealite series 
Space group: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: A2/a 
Dana class: 29.6.3.1 (29) Hydrated Acid and Sulfates (29.6)where A XO4 . x(H2O) (29.6.3) Dana Group 
Geological context
High temperature: Stable at room temperature 
Geological context: Gypsum is one of the more common minerals in sedimentary environments. It is a major rock forming mineral that produces massive beds, usually from precipitation out of highly saline waters. Since it forms easily from saline water, gypsum can have many inclusions of other minerals and even trapped bubbles of gas and water. Occus as a ageing products in mineral waste, slags, MSWI bottom ash, or as secondary product from APC processes. 
Thermodynamics
Individual properties
Molar weight: 172.172 g/mol  ΔGºf-1,797,387 J/mol ref.  Sº: 193.93 J/mol/K ref. 
  ΔHºf-2,022,946 J/mol ref.  Cp: 186.20 J/mol/K ref. 
Reaction properties
Chemical reaction:  Gypsum = Ca+2 + SO4-2 + 2H2O 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -1.62021439e+3   -2.57234846e-1   8.91506186e+4   5.87385148e+2   -5.34735206e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)-4.60
ΔH°r-1,054 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  -4.66   -4.60   -4.71   -4.99   -5.48   -6.14   -7.00   -8.22 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:186.20 J/mol/K 
b:0.00 J/mol/K2 
c:0.00 J.K/mol 

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