Iron oxide minerals are ubiquitous in nature and often have great influence on the fate and availability of trace elements. Zn is an essential trace element for biological processes, but can be toxic at higher concentration. Zn cycling and availability can be affected by its adsorption on, incorporation in, and release from iron oxides. Ferrihydrite is a metastable nanocrystalline iron oxide and transforms to more crystalline phases when exposed to dissolved Fe(II) under anoxic condition. While such reactions have been widely investigated, the effects of ferrihydrite phase transformations on solid-associated trace element speciation and how such elements impact the resulting mineral products are poorly studied. In addition, it is unknown whether Zn repartitioning during such transformations fractionates trace element stable isotopes. To better understand the behavior of Zn during Fe(II)-induced ferrihydrite transformation, we have investigated the phase transformations of Zn-substituted (2 mol%) ferrihydrite at pH 7 under different Fe(II) concentrations at reaction times up to 40 days. X-ray diffraction patterns of the reaction products reveal that low Fe(II) concentration (0.2 mM) favors the formation of hematite, lepidocrocite, and goethite; whereas high Fe(II) concentration (1 mM) promotes the production of magnetite, lepidocrocite, and goethite. Both transformations processes are associated with the transient release of Zn to solution, which during aging is taken up by the mineral products. Rietveld refinement of the XRD data shows a progressive transformation from ferrihydrite to other iron oxides, with new phase nucleating within a few days but changes continuing over the entire duration of study. Control experiments with Zn-free ferrihydrite observe no hematite formation, indicating that Zn alters ferrihydrite transformation pathways. EXAFS spectroscopy shows that the coordination of solid-associated Zn changed from tetrahedral to a mixture of tetrahedral and octahedral during the transformations. Despite these coordination changes, ferrihydrite transformations produce only a minor fractionation of Zn stable isotopes. This work shows that iron oxide mineralogical transformations occurring at redox interfaces may transiently solubilize trace elements such as zinc. Under conditions with substantial advective fluid flow, this may facilitate mobilization and transport. The minimal isotopic fraction observed suggest that such mobilization may not leave detectable signatures in the remaining iron oxides. More broadly, this study builds on a growing body of work demonstrating the unexpected mobility of iron oxide-associated trace elements under dynamic redox conditions, and raises questions about the long-term viability of coprecipitation as a method of contaminant remediation.