Andalusite

Formula : Al2SiO5

Space group: 
Orthorhombic - Dipyramidal H-M Symbol (2/m 2/m 2/m) Space Group: Pnnm
Dana class: 
Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O (52.2) with cations in [4] and >[4] coordination (52.2.2b) AL2SIO5 (Andalusite subgroup)
High temperature: 
Stable in the range of200 to 800C in a low-pressure domain
Geological context: 
low-pressure metamorphic aluminous rocks, low-pressure aluminous magmas

Dernière mise à jour le 25.01.2021

THERMODYNAMICS

Reaction properties

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

298.15 K, 1 bar log10K: 16.21 ΔH°r:-244610 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K 20.06 16.21 11.65 7.40 3.09 -0.50 -3.65 -6.58