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Growth Of Sparingly-Soluble Ab-Type Minerals As A Function Of Their A:B Ratio, Jacquelyn N. Bracco

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A fundamental understanding of mineral growth kinetics is necessary to predict mineral reactivity in geologic environments. We use hydrothermal atomic force microscopy (HAFM) to measure step advance speeds and morphological evolution of the sparingly-soluble minerals magnesite (MgCO3), barite (BaSO4) and celestite (SrSO4) while systematically varying the concentrations of their constituent cations and anions in solution. For all three minerals, a maximum step velocity is reached at an aqueous cation:anion concentration (r) near unity and decreases with extreme r despite order of magnitude differences in the water exchange rate for the cations comprising the minerals. Affinity based models fail to reproduce …