The fractionation of stable isotopes (e.g., Si, Ca, Mg, Zn, Cu, C, O) provides valuable insight into the processes involved during mineral-fluid interaction. Isotopic measurements can trace contaminant cycling, facilitate tracking of weathering processes, and be used as proxies for past environmental conditions. However, the interpretation of stable isotope signatures in the Earth’s shallow subsurface, or critical zone, is complicated by a lack of known isotope fractionation factors for many reactions, the presence of organic and inorganic ligands that impact fluid speciation and fractionation, and the complex dissolution behaviour of silicates (e.g., non-stoichiometric dissolution). Our research explores the controls on stable isotope fractionation during mineral-fluid interaction and the processes by which isotope compositions of minerals may be altered over time. Our results will provide insight into mechanisms of mineral-fluid interaction, and will help improve isotopic tracers of processes such as CO2 storage by carbon mineralization.