Home > Data consultation > Mineral species
 
Mineral speciesFormula
 GruneriteFe7Si8O22(OH)2 
Mineralogy
Family: Amphibole Group 
Space group: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m 
Dana class: 66.1.1.3 (66) Inosilicate Double-Width Unbranched Chains, W=2 (66.1) Dana Type (66.1.1) Group 1, the Mg-Fe-Mn-Li amphiboles (Monoclinic) 
Geological context
High temperature: Temperature range of stability of grunerite ranges beween around 450-450 to 500-600C it is strongly pressure dependant. 
Geological context: Common in medium- to high-grade metamorphosed iron formations. A product of contact metamorphism, and in some blueschist facies metaquartzites. 
Thermodynamics
Individual properties
Molar weight: 1,001.614 g/mol  ΔGºf-8,936,392 J/mol ref.  Sº: 631.33 J/mol/K ref. 
  ΔHºf-9,623,000 J/mol ref.  Cp: 681.08 J/mol/K ref. 
Reaction properties
Chemical reaction:  Grunerite + 14H+ + 8H2O = 7Fe+2 + 8H4SiO4 
log10(Keq) = A + B.T + C.T-1 + D.log10(T) + E.T−2 (with T expressed in Kelvin)
A B C D E
 -2.47527123e+3   -3.87944777e-1   1.47908087e+5   8.96415463e+2   -6.69151449e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)48.00
ΔH°r-409,914 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  54.59   48.00   40.51   33.78   27.17   21.80   17.10   12.62 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:755.50 J/mol/K 
b:362.00 J/mol/K2 
c:-162.10 J.K/mol 

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