Recovered shipboard solids (rocks and sediments) may be characterized for elemental abundances on International Ocean Discovery Program (IODP) expeditions in several ways, using either the shipboard inductively coupled plasma–atomic emission spectrometer (ICP-AES) or a handheld portable X-ray fluorescence spectrometer (pXRF). These two instruments have overlapping capabilities in terms of the elements they measure but are designed to meet different analytical needs. During Expedition 366, we made extensive use of both instruments to conduct standard bulk elemental analysis of samples and in situ measurements on rock surfaces of cores. The following is a description of current shipboard measurement protocols for recovered rocks and sediments using these instruments, an analysis of the respective methodologies, and recommendations for best analytical practices.