Hnontronite(Ca)

Formula : Ca0.17Fe1.67Al0.67Si3.66O10(OH)2:4.24H2O

Space group: 
Monoclinic - Prismatic HM symbol (2/m) Space Group: C 2/m
Dana class: 
71.3.1a.3VIII- 71 Phyllosilicate Minerals ; 71.3 Phyllosilicates Phyllosilicate Sheets of Six-Membered Rings with 2:1 clays ; 71.3.1a Smectite group (Dioctahedral Smectites)
High temperature: 
Low temperature mineral. At higher temperatures(> 500C), detachment of (OH) ions takes place.
Geological context: 
Nontronite has been formed by the alteration of eruptive igneous rocks. Nontronite is found both in mineral veins (often with opal and quartz) and as an alteration product of volcanic glasses.

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
491.342 210.354 (Ref.: 15bla/vie, 11vie/bla) -5645801 (Ref.: Internal calculation) -6217043 (Ref.: 15bla/vie, 11vie/bla) 575.144 (Ref.: 15bla/vie, 11vie/bla) 647.33 (Ref.: 15bla/vie, 11vie/bla)
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.
647.33 0.00 0.00 (Ref.: 15bla/vie, 11vie/bla)
Reaction properties

Hnontronite(Ca) + 7.36H+ ⇌ 0.67Al+3 + 0.17Ca+2 + 1.67Fe+3 + 3.66H4SiO4

298.15 K, 1 bar log10K: -4.66 ΔH°r:-114584 J·mol-1 (Ref.: 15bla/vie, 11vie/bla)
T(°C) 0 25 60 100 150 200 250 300
log10K -2.98 -4.66 -6.87 -8.98 -11.12 -12.90 -14.54 -16.20
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-2419.067380 -0.328650 147736.890057 855.897212 -8976458.420531