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Mineral speciesFormula
 GlaucophaneNa2(Mg3Al2)Si8O22(OH)2 
Mineralogy
Family: Amphibole Group 
Space group: Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m 
Dana class: 66.1.3c.1 (66) Inosilicate Double-Width Unbranched Chains, W=2 (66.1) Dana Type(66.1.3c) Group 4, the sodic amphiboles 
Geological context
High temperature: The stability of glaucophane is limited tohigher pressures than 4 kb and the upper limit of its stability around 600C. 
Geological context: Metamorphic blue shists. 
Thermodynamics
Individual properties
Molar weight: 783.543 g/mol  ΔGºf-11,230,851 J/mol ref.  Sº: 541.20 J/mol/K ref. 
  ΔHºf-11,964,000 J/mol ref.  Cp: 643.10 J/mol/K ref. 
Reaction properties
Chemical reaction:  Glaucophane + 14H+ + 8H2O = 2Al+3 + 3Mg+2 + 2Na+ + 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
 -2.54539772e+3   -3.94031977e-1   1.50853871e+5   9.17972031e+2   -6.89519624e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)36.98
ΔH°r-397,394 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  43.38   36.98   29.74   23.25   16.91   11.77   7.27   2.99 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:663.00 J/mol/K 
b:422.81 J/mol/K2 
c:-129.75 J.K/mol 

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