10.6084/m9.figshare.3453383.v1 L. E. Morgan L. E. Morgan D. F. Mark D. F. Mark J. Imlach J. Imlach D. Barfod D. Barfod R. Dymock R. Dymock FCs-EK: a new sampling of the Fish Canyon Tuff <sup>40</sup>Ar/<sup>39</sup>Ar neutron flux monitor Geological Society of London 2016 Scottish Universities Environmental Research Centre FC R value Fish Canyon Tuff neutron flux Ar Geology 2016-06-21 11:22:07 Dataset https://geolsoc.figshare.com/articles/dataset/FCs-EK_a_new_sampling_of_the_Fish_Canyon_Tuff_sup_40_sup_Ar_sup_39_sup_Ar_neutron_flux_monitor/3453383 <p>Sanidine from the Fish Canyon Tuff is regularly used as a neutron flux monitor by <sup>40</sup>Ar/<sup>39</sup>Ar geochronologists. A new sampling of the Fish Canyon Tuff (denoted FCs-EK) has yielded sanidine that relative to FC-2 is confirmed here to have an <em>R</em> value of 0.9997±0.0100, which is indistinguishable from 1. The new sample will allow for continuity as many <sup>40</sup>Ar/<sup>39</sup>Ar laboratories have exhausted their supplies of FC-2. FCs-EK is now available in significant quantities from the Scottish Universities Environmental Research Centre. </p>