XPol allows users to observe, zoom and easily toggle between multiple "georegistered" images such as a pair of plane polarized (PPL) and cross-polarized light (XPL) images collected on a petrographic microscope. With the annotation feature turned on, users can label and draw on the images. There is no limit to the number of images that can be loaded at one time. XPol currently uses Dropbox for file management but will soon allow users to use Google Drive or download images to their device to use offline. iPhone and iPad compatible, but iPads are recommended for the best viewing and annotating experience.