Diopside

Formula : CaMg(SiO3)2

Space group: 
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/c
Dana class: 
65.1.3a.1 (65) Inosilicate Single-Width Unbranched Chains, W=1(65.1)with chains P=2 (65.1.3a)C2/c clinopyroxenes (Ca clinopyroxenes)
High temperature: 
The minimal stability temperature of diopside can be estimated around 550C but this latter is strongly dependant on aH2O,aCO2.
Geological context: 
Basic and ultrabasic igneous and metamorphic rocks.

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
216.550 66.090 -3028296 -3202488 143.093 156.90
Reaction properties

Diopside + 4H+ + 2H2O ⇌ Ca+2 + Mg+2 + 2H4SiO4

298.15 K, 1 bar log10K: 21.73 ΔH°r: -158241 J·mol-1
T(°C) 0 25 60 100 150 200 250 300
log10K 24.28 21.73 18.84 16.23 13.68 11.62 9.86 8.24