Cassiterite

Formula : SnO2

Family: 
Oxides
Space group: 
Tetragonal - Ditetragonal Dipyramidal H-M Symbol (4/m 2/m 2/m) Space Group: P 4/mnm
Dana class: 
4.4.1.5 (4)Simple Oxides 4.4)with a cation charge of 4+ (A++++ O2) (4.4.1)Rutile group (Tetragonal: P4/mnm)
High temperature: 
Possible stability around 100C in laboratory experiments, in a natural environnement : hydrothermal and present in magmatic rocks during late pneumatolitic stage; but some data allows to suppose a cassiterite stable during the weathering stage of tin sul
Geological context: 
Occurs in granite pegmatites and alluvial placer deposits.

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
150.709 28.900 (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. -515826 (Ref.: Internal calculation) -577630 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p. 49.040 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p. 53.22 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p.
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.
76.04 7.36 -22.24 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p.
Reaction properties

Cassiterite + 2H+ ⇌ Sn+2 + 0.5O2 + H2O

298.15 K, 1 bar log10K: -45.46 ΔH°r:276957 J·mol-1 (Ref.: 89cox/wag) Cox J.D., Wagman D.D., and Medvedev V.A., 1989. CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 279 p.
T(°C) 0 25 60 100 150 200 250 300
log10K -49.88 -45.46 -40.33 -35.61 -30.93 -27.22 -24.22 -21.78
log10K(T) = A + B·T + C·T-1 + D·log10(T) + E·T−2 (T in Kelvin)
A B C D E
-195.558622 -0.030315 -4882.311297 72.858703 -423832.665698