On the other hand, for some minerals, the ephemeral nature and low concentrations of potential precursor/intermediate species may hinder a possibility to be captured, leading to the potentially incorrect conclusion that such systems behave classically. This is particularly true for Mg-struvite , which has yet to provide clear evidence of involving an amorphous precursor, despite observations of amorphous-like species under specific conditions . Here, we demonstrate that the Mg-struvite formation involves a short-lived (< 10 s) amorphous phase, pointing towards a non-classical nature of the system. Furthermore, we show that the onset of crystallisation manifests itself as a perturbation in the structure of the aqueous medium in which the process takes place. This perturbation potentially indicates a liquid-liquid phase separation (LLPS) as the origin of the amorphous precursor which precedes the actual crystal growth phase .