The Reef Package is a sequence of coarse-grained cumulates that host the J-M Reef Pd-Pt deposit in the Stillwater Complex of Montana. The top of the Reef Package marks the top of economic-grade platinum-group element mineralization and is identified by a distinct change in rock fabric, from the coarse-grained rocks of the Reef Package to finer-grained cumulates in the hanging wall. This dataset tabulates whole-rock major, minor, and trace element geochemistry of rock samples collected from diamond drill holes that intersect the textural discontinuity at the top of the Reef Package from the underground working of the Stillwater Mine. The dataset also tabulates rock fabric data collected by electron backscatter diffraction of polished thin sections collected at the decimeter scale on either side of the hanging wall contact. The rock fabric dataset includes crystal size, shape, and orientation data. This dataset was collected to quantify the geochemical and textural characteristics of the cumulates in and above the Reef Package in order to constrain ore forming processes.