Concentration data for as many as 64 constituents in the six United States Geological Survey's (USGS) Geochemical Exploration Reference Samples (GXR) have been collected from journal articles and technical reports published since these reference materials were issued in 1971. These data are summarized into mean +/‐ one standard deviation values and compared with our previously calculated concentrations based upon USGS round‐robin data published in 1978. All new literature data located are presented in the appendi