These data are sulfur isotope determinations (34S/32S ratios) for sulfur-bearing minerals collected from epithermal veins in the Lowland mining district, Montana, USA and from metasedimentary rocks that host the Black Angel zinc-lead-silver deposit, Greenland. The samples were collected by cooperators as parts of larger ore genesis studies. The determinations were performed between February 2019 and March 2021 on 35 samples of pyrite, sphalerite, galena, and chalcopyrite from Lowland vein occurrences and 5 samples of anhydrite from Black Angel host rocks.