Kaolinite

Formula : Al2Si2O5(OH)4

Space group: 
Triclinic - Pedial H-M Symbol (1) Space Group: P1
Dana class: 
71.1.1.2 (71) Phyllosilicate Sheets of Six-Membered Rings (71.1) with 1:1 layers (71.1.1) Kaolinite group
High temperature: 
This mineral is stable from the room temperature up to 260C in hydrothermal systems.
Geological context: 
Secondary mineral derived from the wathering of alumino-silicate mineral and also from hydrothermal alteration. Replaces other aluminosilicate minerals during hydrothermal alteration and weathering. A common constituent of the clay-size fraction of sediments, where it may be formed by direct precipitation.

Dernière mise à jour le 11.06.2018

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
cm3·mol-1
ΔGºf
J·mol-1
ΔHºf
J·mol-1
J·mol-1·k-1
CP
J·mol-1·K-1
258.160 99.340 -3793935 -4115300 200.900 243.37
Reaction properties

Kaolinite + 6H+ ⇌ 2Al+3 + 2H4SiO4 + H2O

298.15 K, 1 bar log10K: 6.47 ΔH°r: -169718 J·mol-1
T(°C) 0 25 60 100 150 200 250 300
log10K 9.19 6.47 3.35 0.49 -2.39 -4.80 -6.98 -9.08