This data report extends the X-ray diffraction (XRD) work reported in the Expedition Reports section of this volume from approximately 200 samples to 1570 investigated bulk powder samples. The unique central Arctic Ocean samples of the Integrated Ocean Drilling Program Arctic Coring Expedition (Expedition 302), the first mission-specific platform expedition, were collected and prepared by different German groups and provided to the Central Laboratory for Crystallography and Applied Material Sciences (ZEKAM), Geosciences, University of Bremen. The data set reported here is special because all samples were measured on the same diffractometer using the same measurement settings, and the diffractograms were investigated by the same person. Therefore, the data set gives maximum continuity with the onshore party investigation. The Neogene sediments of the Arctic Ocean are dominated by detrital nonbiogenic material. The composition of fine-fraction silicates (clay minerals), the different SiO (sub 2) mineral phases, which dominate much of the Paleogene sections, and the diagenetic overprinting in the whole cores are best deciphered by XRD. Important paleoceanographic and diagenic information were deduced.