The final structure contains many patterns of the rocksalt structure, which spread out in different spatial directions. Furthermore, grain boundaries are formed that make the particle appear amorphous. In summary, we show that a magnesium particle generated from Wulff construction oxidizes first at the surface oct sites from a thermodynamic point of view. Further oxygen adsorption is also thermodynamically favored despite the formed surface oxide layers. The fully oxidized particle exhibits an amorphous structure with rocksalt structure elements but many grain boundaries.