Afwillite

Formula : Ca3Si2O4(OH)6

Space group: 
Monoclinic - Sphenoidal H-M Symbol (2) Space Group: P 21
Dana class: 
52.4.7.1 (52 )Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O (52.4) with cations in [6] and/or > [6] coordination (52.4.7) Afwillite and related species
High temperature: 
Probably related with the weathering. Also as artificial mineral found in the concrete
Geological context: 
A product of contact metamorphism of limestones.

Dernière mise à jour le 19.12.2017

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
cm3·mol-1
ΔGºf
kJ·mol-1
ΔHºf
kJ·mol-1
J·mol-1·k-1
CP
J·mol-1·K-1
342.447 129.530 -4.469.061 -4.853.820 289.702 303.55
Reaction properties

Afwillite + 6H+ ⇌ 3Ca+2 + 2H4SiO4 + 2H2O

298.15 K, 1 bar log10K: 49.42 ΔH°r: -269228 J·mol-1
T(°C) 0 25 60 100 150 200 250 300
log10K 53.77 49.42 44.52 40.16 35.96 32.68 29.97 27.58