In this letter, structure factor calculations and computer simulated powder X-ray diffraction patterns are used to challenge conclusions reached in a recent study by D. Simeone et al. regarding radiation-induced phase transformations in MgAl 2 O 4 spinel. Based on experimental results presented by D. Simeone et al. and previously by other researchers, and based on the structure factor results presented here, spinel most likely succumbs to a phase transformation under irradiation that involves a profound change in the arrangement of cations in the lattice. The space group is modified by the transformation and the new, metastable structure is most likely a defective rocksalt structure. These conclusions are at odds with the description of the spinel metastable phase offered by Simeone et al.