Abstract

The complexity of silicate minerals makes prediction of their dissolution rates a challenging problem. A combination of large cluster ab-initio quantum mechanical models and chemical probe dissolution experiments are used to understand the dissolution process for olivine-group minerals. Rapid release of M2+ cations by precursor reactions involving H+ attack at μ3-O surface sites produces a silica-enriched surface. Slower rates of silica release via a ligand exchange reaction involving a proton in the activated complex controls the overall rate of olivine dissolution. Our results provide a physical explanation for the correlation among olivine dissolution rates and water exchange rates for the corresponding aqueous cation.

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