Element maps of ultramafic samples (peridotites and pyroxenites) taken from drill core recovered from IODP Site U1601 on the Atlantis Massif (Mid-Atlantic Ridge) during IODP Expedition 399 (https://iodp3.org/expedition/399/). A total of 114 samples were selected to cover the full 1268 m depth of Hole U1601C as well as its lithological and textural variability. The data document the distribution of any element in excess of ~0.2wt% across the samples and take the form of x-y-count .txt files. Samples comprised standard size geological thin sections, or, in the case of samples with an MBIO suffix, polished billets. The data document the mineral major- and minor element composition as measured by EDS-SEM in thin section, or, in the case of samples with an MBIO suffix, polished billets.