Amesite

Formula : Mg4Al2(Al2Si2)O10(OH)8

Space group: 
Triclinic - Pedial H-M Symbol (1) Space Group: C1
Dana class: 
7.1.2c.1 (71) Phyllosilicate Sheets of Six-Membered Rings (71.1) with 1:1 layers(71.1.2c)Serpentine group (Amesite subgroup)
High temperature: 
Based on the chlorite s.l., chlorite may be stable from about 100C to 600C and more with the increase of the pressure.
Geological context: 
A product of low-grade metamorphism of Al, Mg-rich rocks.

Dernière mise à jour le 25.01.2021

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
 V°
cm3·mol-1
 ΔGºf
J·mol-1
 ΔHºf
J·mol-1
 Sº
J·mol-1·k-1
 CP
J·mol-1·K-1
557.370 205.200 (Ref.: 05vid/par) Vidal O., Parra T., Vieillard, P., 2005. Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation. American Mineralogist 90, 347-358. -8365841 (Ref.: Internal calculation) -9035900 (Ref.: 05vid/par) Vidal O., Parra T., Vieillard, P., 2005. Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation. American Mineralogist 90, 347-358. 403.200 (Ref.: 05vid/par) Vidal O., Parra T., Vieillard, P., 2005. Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation. American Mineralogist 90, 347-358. 516.34 (Ref.: 05vid/par) Vidal O., Parra T., Vieillard, P., 2005. Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation. American Mineralogist 90, 347-358.
CP(T) = a + b·T + ·c·T-2 (T in Kelvin)
a
J·mol-1·K-1
 b * 103
J·mol-1·K-2
 c * 10-5
J·K·mol-1
 Maier Kelley Ref.
631.95 282.68 -177.69 (Ref.: 05vid/par) Vidal O., Parra T., Vieillard, P., 2005. Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation. American Mineralogist 90, 347-358.
Reaction properties

Amesite + 20H+ ⇌ 4Al+3 + 4Mg+2 + 2H4SiO4 + 10H2O

298.15 K, 1 bar log10K: 69.41 ΔH°r:-761722 J·mol-1 (Ref.: 05vid/par) Vidal O., Parra T., Vieillard, P., 2005. Thermodynamic properties of the Tschermak solid solution in Fe-chlorite: Application to natural examples and possible role of oxidation. American Mineralogist 90, 347-358.
T(°C) 0 25 60 100 150 200 250 300
log10K 81.54 69.41 55.37 42.54 29.81 19.44 10.46 2.16
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-4061.534594 -0.615448 255381.533277 1453.142173 -12251219.118009