Okenite

Formula : CaSi2O4(OH)2:H2O

Space group: 
Triclinic Space Group: P1 or P1
Dana class: 
72.3.2.5 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings (72.3)with 3-, 4-, or 5-membered rings and 8-membered rings (72.3.2) Tobermorite group (5- & 8-membered rings)
High temperature: 
Described with the cement phases the stability of Okenite at low temperature cannot be dismissed.
Geological context: 
Secondary mineral from the alteration of basalts.

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
212.277 94.770 -2881719 -3135700 206.746 210.70
Reaction properties

Okenite + 2H+ + H2O ⇌ Ca+2 + 2H4SiO4

298.15 K, 1 bar log10K: 9.18 ΔH°r: -43858 J·mol-1
T(°C) 0 25 60 100 150 200 250 300
log10K 9.90 9.18 8.40 7.76 7.18 6.77 6.43 6.12