Magnesium (Mg) is a very active metal and fine Mg metal powders exposed to atmosphere will be oxidized to a certain degree. However, the amount of oxidation was difficult to measure because each Mg powder basically becomes a sphere consisting of a surface oxide shell and a metal core. In one of the applications, it became critical for our client to find out how much of the powders had already converted into oxides. Technical staff at EMSL developed a novel XRD method, and successfully determined the weight percentage of magnesium oxide in the samples.