Pyrophyllite

Formula : Al2Si4O10(OH)2

Space group: 
Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1
Dana class: 
71.2.1.1 (71) Phyllosilicate Sheets of Six-Membered Rings (71.2) with 2:1 Layers 71.2.1) Pyrophyllite-talc group
High temperature: 
Pyrophyllite stability domains range between 200 to 300C.
Geological context: 
Pyrophyllite occurs in metamorphic aluminous rocks and in hydrothermal haloes.

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
360.314 128.100 -5266218 -5640000 239.760 293.76
Reaction properties

Pyrophyllite + 6H+ + 4H2O ⇌ 2Al+3 + 4H4SiO4

298.15 K, 1 bar log10K: -0.46 ΔH°r: -138257 J·mol-1
T(°C) 0 25 60 100 150 200 250 300
log10K 1.75 -0.46 -3.01 -5.35 -7.74 -9.79 -11.69 -13.59