Pargasite

Formula : Na(Ca2Mg4Al)(Al2Si6)O22(OH)2

Family: 
Amphiboles
Space group: 
Monoclinic - Prismatic H-M Symbol (2/m) Space Group: C 2/m
Dana class: 
66.1.3a.12 (66 )Inosilicate Double-Width Unbranched Chains, W=2 (66.1)Dana Type (66.1.3a)Group 2, the calcic amphiboles
High temperature: 
Stability domain limited near 300C to more 600C is also limited to high pressure, several kbar.
Geological context: 
In metamorphosed limestones and metamorphosed ultramafic and mafic rocks, and in fresh magmatic igneous rocks.

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
835.825 273.500 (Ref.: 78hel/del,92ajoh) -11910710 (Ref.: 78hel/del,92ajoh) -12622091 (Ref.: Internal calculation) 669.440 (Ref.: 78hel/del,92ajoh) 676.71 (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.
861.07 174.31 -210.08 (Ref.: 78hel/del,92ajoh)
Reaction properties

Pargasite + 22H+ ⇌ 3Al+3 + 2Ca+2 + 4Mg+2 + Na+

298.15 K, 1 bar log10K: 104.56 ΔH°r:-940614 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K 119.39 104.56 87.10 71.05 55.12 42.24 31.22 21.17
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-5796.293876 -0.827009 375559.689437 2065.206412 -19772394.412958