Abstract: This data set contains measurements of impurities and ions in three polar ice cores: the Vostok 5G ice core and the Byrd ice core from Antarctica, and the Greenland Ice Sheet Project 2 (GISP2) D core. Parameters include sample depth, grain size, ion concentration, and ice core impurity information. Measurements were made using Ion Chromatography (IC), optical microscopy, and Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM/EDS). Data are available via FTP in Microsoft Excel (.xls)and Microsoft Word (.doc) formats.