Precipitation and Dissolution of Alkaline Earth Sulfates: Kinetics and Surface Energy

Dissolution kinetics and topographic relaxation on celestite (001) surfaces: The effect of solution saturation state studied using Atomic Force Microscopy

“…(9), r is the celestite surface free energy, l is bulk shear modulus, b d is the Burgers vector of the dislocation and K (=1 À m, for an edge dislocation, which is assumed) is calculated from the Poisson ratio m, the ratio of latitudinal to longitudinal strain due to an applied load on the mineral. Using b d = 5.35 · 10 À8 cm and literature values for r = 75.67 mJ m À2 (Hina and Nancollas, 2000), K = 0.6 (Mavko et al, 1998) and l = 17.15 · 10 9 N/m 2 (Mavko et al, 1998), a value of X crit = 0.7 ± 0.2 was obtained. The graph in Fig.…”

“…The difference between predicted (0.7 ± 0.2) and experimental (0.14 ± 0.02) values could be due to a surface energy considerably larger than that used in the prediction of X crit or from a magnitude of the Burgers vector less than that considered in the calculations. The interfacial tension values summarized in Hina and Nancollas (2000) were determined from homogeneous nucleation experiments and crystallite size-dependent solubility. The range of values reported (43-103 mJ m À2 ) were used in estimating the uncertainty in X crit , but it is also reasonable that these interfacial tension quantities may be systematically lower than relevant values to the AFM experiments because the measured quantities may not be directly applicable to the specific crystallographic steps created in the critical etch pit nucleus.…”

Experimental constraints on the evaporation of partially oxidized acid-sulfate waters at the martian surface

“…3 and 7, it is clear that this phase reaches a slight degree of supersaturation before fractionation of Ca from solution is observed. This slight discrepancy is most likely due to a higher degree of supersaturation needed to overcome energy barriers associated with nucleation and crystallization (Hina and Nancollas, 2000). Overall, however, the discrepancy is limited to a maximum SI value of 0.1522 and represents good agreement between calculated and observed mineral precipitation and saturation points for gypsum.…”

Questa baseline and pre-mining ground-water quality investigation. 25. Summary of results and baseline and pre-mining ground-water geochemistry, Red River Valley, Taos County, New Mexico, 2001-2005

“…There are at least four possible reasons for this supersaturation. Freshly precipitated barite can be so fine grained that there is a grain-size, or surface-area, effect on the equilibrium solubility (Balarew, 1925;Hina and Nancollas, 2000). A related possibility is that colloidal particles of barite are not adequately filtered during field filtration.…”