Home > Data consultation > Mineral species
 
Mineral speciesFormula
 BrushiteCaHPO4:2H2O 
Mineralogy
Family: Brushite - Churchite-(Dy) series 
Space group: Monoclinic - Prismatic HM symbol (2/m) Space Group: I2/a 
Dana class: 39.1.1.1VII - 39 Hydrated Acid Phosphates, etc ; 39.1 Hydrated Acid Phosphates, etc A+ [HXO4] . x(H2O) ; 39.1.1 
Geological context
High temperature: Sable at room temperature 
Geological context: Occurs as the most common cave minerals, in guano deposits, and in phosphorites, formed at low pH by reaction of phosphate-rich solutions with calcite and clay. 
Thermodynamics
Individual properties
Molar weight: 172.088 g/mol  ΔGºf-2,160,814 J/mol ref.  Sº: 189.45 J/mol/K ref. 
  ΔHºf-2,409,885 J/mol ref.  Cp: 200.45 J/mol/K ref. 
Reaction properties
Chemical reaction:  Brushite + H+ = Ca+2 + H2PO4- + 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
 -9.00254810e+2   -1.51024699e-1   4.74938112e+4   3.29941410e+2   -2.65157331e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)0.60
ΔH°r-7,375 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  0.70   0.60   0.43   0.21   -0.14   -0.59   -1.16   -1.95 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:31.72 J/mol/K 
b:569.44 J/mol/K2 
c:-0.93 J.K/mol 

Home | Legal information | Private area | Contact us | RSS 2.0 BRGM − 3, avenue Claude Guillemin − 45060 Orléans Cedex 2