There is ongoing recognition of the complex nature of mineral dissolution and growth reactions, observable even in relatively simple chemical systems. Direct observations of mineral-surface interaction (AFM, VSI) shows this complexity in the form of a large diversity of simultaneous rates. With increasing numbers of observations in time or space, this diversity does not converge to yield a narrow distribution of rates that can be easily described by apparent rate laws having simple dependencies on the concentration of dissolved components, the availability of surface area, or similar terms.As an example of this behaviour, we show the results of near-continuous observations of a fixed area of a large single crystal. These observations reveal competitive surface processes ranging from nucleation, growth, and annihilation of short-lived, shallow pits (nm) to long term development of deep (�m) screw dislocations, whose interaction also gives rise to the evolution of macroscopic features that coalesce in large scale reactive fronts. We illustrate how this observed dispersion of rates can be treated statistically, and show how simulative modelling techniques can be used to understand the relationship between stochastic variation of rates and the surface reaction mechanisms available.

Treatment of stochastic mineral surface reactions

247th National Meeting (2014)

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