Minnesotaite

Formula : Fe3Si4O10(OH)2

Space group: 
Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: C1
Dana class: 
71.2.1.5 (71) Phyllosilicate Sheets of Six-Membered Rings (71.2) with 2:1 Layers (71.2.1) Pyrophyllite-talc group
High temperature: 
Minnesotaite would be stable over a wide range of pressure temperature conditions, ranging from a minimum of that determined for talc (90C or less) to maximal conditions of those associated with the transition from the biotite to garnet zones, as shown b
Geological context: 
banded iron formations of northern Minnesota in association with quartz, siderite, stilpnomelane, greenalite and magnetite. In addition to the low grade metamorphic banded iron formations it has also been reported as an alteration mineral associated with sulfide bearing veins.

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
473.892 148.500 (Ref.: 83miy/kle) Miyano T, Klein C (1983 a) Phase relations of orthopyroxene, olivine, and grunerite in high-grade metamorphic iron-formation.Am Mineral 68:699-716 -4474753 (Ref.: Internal calculation) -4822990 (Ref.: 83miy/kle) Miyano T, Klein C (1983 a) Phase relations of orthopyroxene, olivine, and grunerite in high-grade metamorphic iron-formation.Am Mineral 68:699-716 350.800 (Ref.: 83miy/kle) Miyano T, Klein C (1983 a) Phase relations of orthopyroxene, olivine, and grunerite in high-grade metamorphic iron-formation.Am Mineral 68:699-716 364.40 (Ref.: 83miy/kle) Miyano T, Klein C (1983 a) Phase relations of orthopyroxene, olivine, and grunerite in high-grade metamorphic iron-formation.Am Mineral 68:699-716
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.
411.38 125.52 -75.03 (Ref.: 83miy/kle) Miyano T, Klein C (1983 a) Phase relations of orthopyroxene, olivine, and grunerite in high-grade metamorphic iron-formation.Am Mineral 68:699-716
Reaction properties

Minnesotaite + 6H+ + 4H2O ⇌ 3Fe+2 + 4H4SiO4

298.15 K, 1 bar log10K: 14.94 ΔH°r:-139134 J·mol-1 (Ref.: 83miy/kle) Miyano T, Klein C (1983 a) Phase relations of orthopyroxene, olivine, and grunerite in high-grade metamorphic iron-formation.Am Mineral 68:699-716
T(°C) 0 25 60 100 150 200 250 300
log10K 17.02 14.94 12.28 9.77 7.27 5.25 3.47 1.74
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-2339.702749 -0.312096 146910.337608 830.662154 -8930619.280791