The effects of ball milling on hydrous and anhydrous potash alum (potassium aluminum sulfate dodecahydrate, KAl(SO4)(2)???12H(2)O) were investigated by powder X-ray diffraction (XRD), Raman spectroscopy, and energy-dispersive X-ray spectroscopy. The XRD patterns for the milled hydrous samples showed that the crystal structure was unchanged even after 120?h of milling at 12?Hz, except for a lattice expansion and appearance of peaks corresponding to Al2O3 and Fe2O3. The XRD and Raman peaks of milled anhydrous potash alum were broader than those of the unmilled sample. The broadening of Bragg peaks for milled anhydrous potash alum is presumably caused by a decrease in crystallite size and degradation in crystallinity, rather than by amorphization.