A Microkinetic Model of Calcite Step Growth.

In spite of decades of research, mineral growth models based on ion attachment and detachment rates fail to predict behavior beyond a narrow range of conditions. Here we present a microkinetic model that accurately reproduces calcite growth over a very wide range of published experimental data for solution composition, saturation index, pH and impurities. We demonstrate that polynuclear complexes play a central role in mineral growth at high supersaturation and that a classical complexation model is sufficient to reproduce measured rates. Dehydration of the attaching species, not the mineral surface, is rate limiting. Density functional theory supports our conclusions. The model provides new insights into the molecular mechanisms of mineral growth that control biomineralization, mineral scaling and industrial material synthesis.