Commercially available samples of anhydrous MgSO 4 from two different suppliers and the MgSO 4 • 7H 2 O sample were highly crystalline and agreed closely with the patterns simulated from the crystal structure. The MgSO 4 •H 2 O sample showed much broader peaks, indicative of smaller particle/domain size. It largely agreed with the pattern simulated from the monohydrate crystal structure, but additional peaks at 2θ ≈ 20 • , 32 All measured and simulated PXRD patterns can be found in the supporting information.