Annite

Formula : KFe3(AlSi3)O10(OH)2

Family: 
Space group: 
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m
Dana class: 
71.2.2b.3 (71)Phyllosilicate Sheets of Six-Membered Rings (71.2)with 2:1 Layers (71.2.2b) Mica Group (Biotite subgroup)
High temperature: 
Stable to250 to 600C in hydrothermal systems, above 1000C for meamorphic events.
Geological context: 
Hydrothermal to igneous mineral.

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
511.886 154.320 -4782450 -5130970 424.020 389.87
Reaction properties

Annite + 10H+ ⇌ Al+3 + 3Fe+2 + K+ + 3H4SiO4

298.15 K, 1 bar log10K: 32.76 ΔH°r: -313153 J·mol-1
T(°C) 0 25 60 100 150 200 250 300
log10K 37.78 32.76 27.01 21.78 16.59 12.33 8.62 5.13