Chamosite(Daphnite)

Formula : Fe5Al(AlSi3)O10(OH)8

Space group: 
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m
Dana class: 
71.4.1.4 (71)Phyllosilicate Sheets of Six-Membered Rings (71.4)interlayered 1:1, 2:1, and octahedra (71.4.1)Chlorite group (Tri-Dioctahedral)
High temperature: 
Metamorphosed iron deposits : lower limit of stability is probabily near ambiant, upper stability limit around 650C.
Geological context: 
Contact, hydrothermal, and regional metamorphism of mafic minerals. 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
713.507 215.880 (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. -6506859 (Ref.: Internal calculation) -7120845 (Ref.: 01vid/par) Vidal, O., Parra, T. and Trotet, F (2001): A thermodynamic model for Fe-Mg aluminous chlorite using data from phase equilibrium experiments and natural pelitic assemblages in the 100-600C, 1-25 kbar P-T range. Am. J. Sci., 301, 557-592. 559.400 (Ref.: 01vid/par) Vidal, O., Parra, T. and Trotet, F (2001): A thermodynamic model for Fe-Mg aluminous chlorite using data from phase equilibrium experiments and natural pelitic assemblages in the 100-600C, 1-25 kbar P-T range. Am. J. Sci., 301, 557-592. 574.76 (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.
599.55 372.81 -120.85 (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

Chamosite(Daphnite) + 16H+ ⇌ 2Al+3 + 5Fe+2 + 3H4SiO4 + 6H2O

298.15 K, 1 bar log10K: 47.60 ΔH°r:-497518 J·mol-1 (Ref.: 01vid/par) Vidal, O., Parra, T. and Trotet, F (2001): A thermodynamic model for Fe-Mg aluminous chlorite using data from phase equilibrium experiments and natural pelitic assemblages in the 100-600C, 1-25 kbar P-T range. Am. J. Sci., 301, 557-592.
T(°C) 0 25 60 100 150 200 250 300
log10K 55.47 47.60 38.39 29.96 21.58 14.75 8.78 3.17
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-3742.235484 -0.547893 231853.379771 1338.448044 -12120616.463384