We present the results of 276 X-ray diffraction analyses of bulk sediment from Brazos-Trinity IV (Integrated Ocean Drilling Program [IODP] Hole U1320A) and Ursa (IODP Hole U1324B) Basins. The mineralogy at both locations is qualitatively very similar, with quartz and phyllosilicates dominating the assemblages and calcite, dolomite, K-feldspars, plagioclases, and halite present in varying amounts. Ankerite (iron-rich dolomite) was observed in only one sample. Although the composition of the sediment is relatively monotonous, trends in the percent occurrence of each fraction are observed and can be linked to changes in the lithostratigraphic units and core descriptions from Expedition 308. The data presented here will help establish a link between geomechanical behaviors of the sediments and matrix effects driven by mineral composition.