Kyanite

Formula : Al2SiO5

Space group: 
Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1
Dana class: 
52.2.2c.1 (52) Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O (52.2 )with cations in [4] and >[4] coordination (52.2.2c) Al2SiO5 Kyanite subgroup)
High temperature: 
Stable in the range of200 to 800C. Its stability depends also on pressure.
Geological context: 
Metamorphic aluminous rocks, aluminous magmas

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
162.046 44.090 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp. -2430720 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp. -2581169 (Ref.: Internal calculation) 83.680 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp. 121.06 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp.
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.
173.19 28.52 -53.90 (Ref.: 78hel/del) Helgeson, H.C., Delany, J.M, Nesbitt, H.W., and Bird, D.K., 1978. Summary and Critique of the Thermodynamic Properties of Rock Forming Minerals: Amer. J. Sci., 278A, 229 pp.
Reaction properties

Kyanite + 6H+ ⇌ 2Al+3 + H4SiO4 + H2O

298.15 K, 1 bar log10K: 15.94 ΔH°r:-240322 J·mol-1 (Ref.: Internal calculation)
T(°C) 0 25 60 100 150 200 250 300
log10K 19.73 15.94 11.46 7.28 3.04 -0.49 -3.60 -6.50
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-1344.779879 -0.205817 85324.147893 478.771922 -4336948.127769