Crystallization of solid solutions from aqueous solutions in a porous medium: zoning in (Ba, Sr) SO4

Article Abstract:

Compositional zoning by the synthesis of Barite-celestite solid solutions, under controlled conditions by the counter-diffusion of doubly ionized barium, strontium and sulphate ions through a porous transport medium such as silica gel, reveals that high super saturation rates of crystallization leads to oscillatory zoning phenomena, which needs no externally controlled alteration of intensive parameters. The threshold of supersaturation for nucleation is much higher for barite than for celestite as it is inversely related to the solubility. Zoning is periodic and sector-controlled with many of the general features observed in natural minerals at high supersaturations.

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Experimentally determined partitioning of Rb between richterites and aqueous (Na, K)-chloride solutions

Article Abstract:

A study was conducted to analyze the distribution of Rb-Na and Rb-K between richterite and a 2-molal aqueous (Na, K, Rb)-chloride solution. Hydrothermal experiments were carried out at 800 degrees C. The solid products were characterized by more than 90 wt % amphiboles with different amounts of quartz. Results indicated that K-Rb fractionation between alkali amphiboles and fluids were different from K-Rb fractionation between alkali feldspar/phlogopite and fluid.

Chlorides, Rubidium, Mineral-melt partitioning

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Fluid supersaturation and crystallization in porous media

Article Abstract:

A study of fluid crystallization in rocks through nucleation of sulfates and carbonates of Ba and Sr indicates the dependence of supersaturation on the transport properties of the crystallizing medium. Salt solubilities, medium porosity and rate of supersaturation decide the optimum value of supersaturation, beyond which nucleation occurs. An increase in temperature restricts solute movement and hence induces supersaturation.

Porous materials, Nucleation, Nucleation (Chemistry)

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