Wollastonite

Formula : CaSiO3

Space group: 
Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1
Dana class: 
65.2.1.1a (65) Inosilicate Single-Width Unbranched Chains, W=1 (65.2) with chains P=3 (65.2.1) Wollastonite group
High temperature: 
It is a high temperature mineral ranguing between around 400C to up to 1000C, its stability is strongly dependent on the CO2 fugacity.
Geological context: 
Common in thermally metamorphosed siliceous carbonates, the intruding igneous rock, and skarn deposits along their contact; also in some alkalic igneous rocks and carbonatites. This mineral occurs also in slags from smelters and MSWI bottom ash.

Dernière mise à jour le 25.01.2021

THERMODYNAMICS

Individual properties (298.15 K)
M
g·mol-1
 V°
cm3·mol-1
 ΔGºf
J·mol-1
 ΔHºf
J·mol-1
 Sº
J·mol-1·k-1
 CP
J·mol-1·K-1
116.162 39.930 (Ref.: 78hel/del,92ajoh) -1544737 (Ref.: Internal calculation) -1630045 (Ref.: 78hel/del,92ajoh) 82.006 (Ref.: 78hel/del,92ajoh) 85.26 (Ref.: 78hel/del,92ajoh)
CP(T) = a + b·T + ·c·T-2 (T in Kelvin)
a
J·mol-1·K-1
 b * 103
J·mol-1·K-2
 c * 10-5
J·K·mol-1
 Maier Kelley Ref.
111.46 15.06 -27.28 (Ref.: 78hel/del,92ajoh)
Reaction properties

Wollastonite + 2H+ + H2O ⇌ Ca+2 + H4SiO4

298.15 K, 1 bar log10K: 14.05 ΔH°r:-85986 J·mol-1 (Ref.: 78hel/del,92ajoh)
T(°C) 0 25 60 100 150 200 250 300
log10K 15.39 14.05 12.44 10.94 9.46 8.26 7.24 6.31
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-631.847838 -0.086944 41722.732404 225.630380 -2349401.293034