Home > Data consultation > Mineral species
 
Mineral speciesFormula
 Cronstedtite(Th)Fe3SiAlO5(OH)4 
Mineralogy
Family: Kaolinite-Serpentine Group 
Space group: Trigonal - Ditrigonal Pyramidal H-M Symbol (3m) Space Group: P 31m 
Dana class: 71.1.2c.7 (71) Phyllosilicate Sheets of Six-Membered Rings (71.1) with 1:1 layers (71.1.2c) Serpentine group (Amesite subgroup) 
Geological context
High temperature: Cronstedtite is stable at low temperature in iron-rich medium. 
Geological context: A low-temperature hydrothermal product in ore veins. 
Thermodynamics
Individual properties
Molar weight: 370.634 g/mol  ΔGºf-2,613,709 J/mol ref.  Sº: 304.59 J/mol/K ref. 
  ΔHºf-2,914,550 J/mol ref.  Cp: 307.60 J/mol/K ref. 
Reaction properties
Chemical reaction:  Cronstedtite(Th) + 10H+ = Al+3 + 2Fe+2 + H4SiO4 + Fe+3 + 5H2O 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -1.71983634e+3   -2.66661143e-1   1.27266941e+5   6.16641860e+2   -4.81407316e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)99.20
ΔH°r-644,313 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  111.11   99.20   85.54   73.09   60.81   50.98   42.77   35.58 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:307.60 J/mol/K 
b:0.00 J/mol/K2 
c:0.00 J.K/mol 

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