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Mineral speciesFormula
 AnthophylliteMg7Si8O22(OH)2 
Mineralogy
Family: Amphibole Group 
Space group: Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: P nma 
Dana class: 66.1.2.2 (66) Inosilicate Double-Width Unbranched Chains, W=2 (66.1) Dana Type (66.1.2) Group 1, the Mg-Fe-Mn-Li amphiboles (Orthorhombic) 
Geological context
High temperature: Anthophyllite is stable from 200C to about 700C. 
Geological context: Occurs from medium- or high-grade metamorphism, in amphibolites, gneisses, metaquartzites, iron formations, granulites, and schists derived from argillaceous sediments, ultramafic, or mafic igneous rocks; also a retrograde reaction product. 
Thermodynamics
Individual properties
Molar weight: 780.820 g/mol  ΔGºf-11,343,357 J/mol ref.  Sº: 534.50 J/mol/K ref. 
  ΔHºf-12,070,000 J/mol ref.  Cp: 663.01 J/mol/K ref. 
Reaction properties
Chemical reaction:  Anthophyllite + 14H+ + 8H2O = 7Mg+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
 -2.66087411e+3   -4.06379117e-1   1.67764788e+5   9.59387209e+2   -7.18712607e+6 
Van t'Hoff
@ 25°C, 1 bar: log 10(Keq)73.74
ΔH°r-601,914 J/mol ref.
T (ºC) : 0 25 60 100 150 200 250 300
log 10(Keq):  83.43   73.74   62.76   52.91   43.32   35.67   29.19   23.29 
Maier Kelley
Cp(T) = a + b*10-3T + C*105T-2 (with T expressed in Kelvin)  ref.
a:815.11 J/mol/K 
b:248.20 J/mol/K2 
c:-200.99 J.K/mol 

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