Beidellite(Mg)

Formula : Mg0.17Al2.34Si3.66O10(OH)2

Space group: 
Monoclinic - Prismatic HM symbol (2/m) Space Group: C 2/m or ORTH
Dana class: 
71.3.1a.1VIII- 71 Phyllosilicate Minerals ; 71.3 Phyllosilicates Phyllosilicate Sheets of Six-Membered Rings with 2:1 clays ; 71.3.1a Smectite group (Dioctahedral Smectites)
High temperature: 
Low temperature mineral. At higher temperatures(> 500C), detachment of (OH) ions takes place.
Geological context: 
Montmorillonite and beidellite are the principal constituent of bentonite clay deposits. These have been formed by the alteration of eruptive igneous rocks. They occur in sedimentary and metamorphic rocks, in deposits of hydrothermal origin, and soils, and are useful in the preparation of ceramics, drilling muds, paper, rubber, paints and moulding sands.

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
364.070 130.110 (Ref.: 15bla/vie) Blanc, P., Vieillard, P., Gailhanou, H., Gaboreau, S., Gaucher, E.C., Fialips, C.I., Made, B., Giffaut, E., 2015. A generalized model for predicting the thermodynamic properties of clay minerals. American Journal of Science 315, 734-780. -5354378 (Ref.: Internal calculation) -5723810 (Ref.: 15bla/vie) Blanc, P., Vieillard, P., Gailhanou, H., Gaboreau, S., Gaucher, E.C., Fialips, C.I., Made, B., Giffaut, E., 2015. A generalized model for predicting the thermodynamic properties of clay minerals. American Journal of Science 315, 734-780. 263.130 (Ref.: 15bla/vie) Blanc, P., Vieillard, P., Gailhanou, H., Gaboreau, S., Gaucher, E.C., Fialips, C.I., Made, B., Giffaut, E., 2015. A generalized model for predicting the thermodynamic properties of clay minerals. American Journal of Science 315, 734-780. 303.74 (Ref.: 15bla/vie) Blanc, P., Vieillard, P., Gailhanou, H., Gaboreau, S., Gaucher, E.C., Fialips, C.I., Made, B., Giffaut, E., 2015. A generalized model for predicting the thermodynamic properties of clay minerals. American Journal of Science 315, 734-780.
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.
303.74 0.00 0.00 (Ref.: 15bla/vie) Blanc, P., Vieillard, P., Gailhanou, H., Gaboreau, S., Gaucher, E.C., Fialips, C.I., Made, B., Giffaut, E., 2015. A generalized model for predicting the thermodynamic properties of clay minerals. American Journal of Science 315, 734-780.
Reaction properties

Beidellite(Mg) + 7.36H+ + 2.64H2O ⇌ 2.34Al+3 + 0.17Mg+2 + 3.66H4SiO4

298.15 K, 1 bar log10K: 5.24 ΔH°r:-200276 J·mol-1 (Ref.: 15bla/vie) Blanc, P., Vieillard, P., Gailhanou, H., Gaboreau, S., Gaucher, E.C., Fialips, C.I., Made, B., Giffaut, E., 2015. A generalized model for predicting the thermodynamic properties of clay minerals. American Journal of Science 315, 734-780.
T(°C) 0 25 60 100 150 200 250 300
log10K 8.29 5.24 1.44 -2.17 -5.83 -8.86 -11.56 -14.15
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-2469.819094 -0.339741 154732.378275 873.131304 -9167151.359531