Antigorite

Formula : Mg48Si34O85(OH)62

Space group: 
Monoclinic - Domatic H-M Symbol (m) Space Group: Cm
Dana class: 
71.1.2a.1 (71) Phyllosilicate Sheets of Six-Membered Rings (71.1)with 1:1 layers (71.1.2a)Serpentine group
High temperature: 
As a replacement of siliceous dolostone along contacts with diabase sills. Antigorite may be stable from about 200C to 650C, its stability domain is strongly dependant on the fugacity of the water.
Geological context: 
Commonly replaces ultramafic rocks, pervasively or in crosscutting veinlets.

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
4535.950 1754.800 (Ref.: 98hol/pow) Holland T.J.B., and Powell R., 1998. An internally consistent thermodynamic data set for phases of petrological interest. Journal of Metamorphic Geology, 16, p. 309 343. -66126875 (Ref.: Internal calculation) -71417980 (Ref.: 98hol/pow) Holland T.J.B., and Powell R., 1998. An internally consistent thermodynamic data set for phases of petrological interest. Journal of Metamorphic Geology, 16, p. 309 343. 3591.000 (Ref.: 98hol/pow) Holland T.J.B., and Powell R., 1998. An internally consistent thermodynamic data set for phases of petrological interest. Journal of Metamorphic Geology, 16, p. 309 343. 4370.46 (Ref.: 98hol/pow) Holland T.J.B., and Powell R., 1998. An internally consistent thermodynamic data set for phases of petrological interest. Journal of Metamorphic Geology, 16, p. 309 343.
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.
5074.25 2253.72 -1222.94 (Ref.: 98hol/pow) Holland T.J.B., and Powell R., 1998. An internally consistent thermodynamic data set for phases of petrological interest. Journal of Metamorphic Geology, 16, p. 309 343.
Reaction properties

Antigorite + 96H+ ⇌ 48Mg+2 + 34H4SiO4 + 11H2O

298.15 K, 1 bar log10K: 500.08 ΔH°r:-3743421 J·mol-1 (Ref.: 98hol/pow) Holland T.J.B., and Powell R., 1998. An internally consistent thermodynamic data set for phases of petrological interest. Journal of Metamorphic Geology, 16, p. 309 343.
T(°C) 0 25 60 100 150 200 250 300
log10K 559.15 500.08 431.01 368.63 308.30 260.84 221.03 184.81
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-29383.248561 -4.019598 1873854.880329 10481.454653 -101235815.226830