Muscovite(disordered)

Formula : KAl2(AlSi3)O10(OH)2

Space group: 
Monoclinic - Prismatic HM symbol (2/m) Space Group: C 2/m
Dana class: 
71.2.2a.1VIII- 71 Phyllosilicate Minerals ; 71.2 Phyllosilicates Phyllosilicate Sheets of Six-Membered Rings with 2:1 Layers ; 71.2.2a Mica Group (Muscovite subgroup)
High temperature: 
The stability domain of muscovite can be established bewteen around 350 - 400C to around 600-700C in the presence of quartz.
Geological context: 
A common rock-forming mineral, in phyllites, schists, and gneisses; in granites, granite pegmatites, and aplites. Formed from other minerals under hydrothermal conditions; may be detrital or authigenic.

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
398.308 140.810 (Ref.: 95rob/hem) Robie R.A., and Hemingway B.S., 1995. Thermodynamic properties of minerals and related substances at 298.15 K and 1 Bar (105 Pascals) pressure and at higher temperatures. U.S. Geol. Survey Bull., 2131, 461 pp. -5593197 (Ref.: Internal calculation) -5974800 (Ref.: 95has/cyg) Haselton H.T., Cygan G.L. and Jenkins D.M., 1995. Experimental study of muscovite stability in pure H 2 O and 1 molal KCl-HCl solutions. Geochimica et Cosmochimica Acta, 59, p. 429-442 287.700 (Ref.: 76rob/hem) Robie R.A., Hemingway B.S. and Wilson H.W. (1976) - The heat capacities of calorimetry conference copper and of muscovite, pyrophylite, and illite between 15 and 375 K and their standard entropies at 298.15 K. J. Research U.S. Geol. Survey., 4, p. 631-644. 326.00 (Ref.: 76rob/hem) Robie R.A., Hemingway B.S. and Wilson H.W. (1976) - The heat capacities of calorimetry conference copper and of muscovite, pyrophylite, and illite between 15 and 375 K and their standard entropies at 298.15 K. J. Research U.S. Geol. Survey., 4, p. 631-644.
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.
335.80 232.25 -70.27 (Ref.: 76rob/hem) Robie R.A., Hemingway B.S. and Wilson H.W. (1976) - The heat capacities of calorimetry conference copper and of muscovite, pyrophylite, and illite between 15 and 375 K and their standard entropies at 298.15 K. J. Research U.S. Geol. Survey., 4, p. 631-644.
Reaction properties

Muscovite(disordered) + 10H+ ⇌ 3Al+3 + K+ + 3H4SiO4

298.15 K, 1 bar log10K: 14.02 ΔH°r:-269123 J·mol-1 (Ref.: 95has/cyg) Haselton H.T., Cygan G.L. and Jenkins D.M., 1995. Experimental study of muscovite stability in pure H 2 O and 1 molal KCl-HCl solutions. Geochimica et Cosmochimica Acta, 59, p. 429-442
T(°C) 0 25 60 100 150 200 250 300
log10K 18.18 14.02 8.95 4.19 -0.66 -4.74 -8.39 -11.91
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-2586.279192 -0.376071 159869.562611 920.245455 -8966853.406040