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any abandoned mining sites present legacies with increased concentrations of arsenic, antimony, and a range of metals. Field observations identify a number of minerals that could serve as potential solubility-controlling phases. Using calorimetric techniques in our laboratory, we measure thermodynamic properties of such phases, compare them to the observations and to the chemical analyses of aqueous solutions collected in the field, to contemplate which phases actually control mobility of various elements. For antimony, the situation is complicated by conflicting conclusions from geochemical and mineralogical studies which can be, however, resolved by consideration of thermodynamic and kinetic properties of the antimony-bearing minerals. For arsenic, there are variations depending on the physical and chemical properties of the systems, and different phases can be encountered. Behavior of other elements, such as uranium, can be also investigated, from extremely acidic solutions that precipitate salts of U4+ to neutral solutions with uranyl carbonates.
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