Geochemical data include major, minor and trace element results for 42 alkaline silicate igneous rock samples. Samples were collected from natural exposures/outcrops during field work in the Central Montana Alkaline Province (CMAP) during the summer of 2022. All samples were analyzed by the U.S. Geological Survey contract laboratory, SGS Labs. Major, minor, and trace elements were determined via wavelength dispersive X-ray fluorescence (WDXRF), inductively coupled plasma-optical emission spectrometry (ICP-OES) and inductively coupled plasma-mass spectrometry (ICP-MS). Additional analytes determined were carbonate carbon by combustion and infrared detection (IR); gold, platinum, and palladium by lead fusion fire assay and ICP-MS; fluoride by ion-selective electrode; ferrous iron by titration; non-essential and essential water by gravimetric methods, and total sulfur and total carbon by IR. Data are reported in comma-separated values (CSV) files. All column headers are described in the accompanying data dictionary. Geologic reference material preferred and mean values are also provided in the accompanying QAQC_Values.csv.