Mineral compositions for metamorphosed lower crustal xenoliths, central Montana, USA

These data are mineral compositions measured by electron microprobe, presented in the 2012 publication in Geosphere by Barnhart et al. The samples are from the Robinson Ranch and Litte Sand Creek xenolith localities in central Montana, hosted by Eocene volcanics. The mineral chemistry was analyzed as part of an effort to help constrain the age, thermal evolution, metamorphic history, and physical properties (e.g., seismic velocities) of Montana deep crust. Geochronology data for some of these samples are also presented in the Barnhart publication. Two other related publications with similar data for additional Montana samples are a 2011 Contributions to Mineralogy and Petrology paper by Blackburn et al. and a 2012 Geochemistry, Geophysics, and Geosystems paper by Mahan et al.