| Summary: | We performed an interlaboratory comparison study with the aim to determine the accuracy of cosmogenic Ne-21 measurements in quartz. CREU-1 is a natural quartz standard prepared from amalgamated vein clasts which were crushed, thoroughly mixed, and sieved into 125-250 mu m and 250-500 mu m size fractions. 50 aliquots of CREU-1 were analyzed by five laboratories employing six different noble gas mass spectrometers. The released gas contained a mixture of 16-30% atmospheric and 70-84% nonatmospheric (predominantly cosmogenic) Ne-21, defining a linear array on the Ne-22/Ne-20-Ne-21/Ne-20 three isotope diagram with a slope of 1.108 +/- 0.014. The internal reproducibility of the measurements is 21 in good agreement with the formal analytical precision for all participating labs. The external reproducibility of the Ne-21 concentrations between labs, however, is significantly overdispersed with respect to the reported analytical precision. We report an average reference concentration for CREU-1 of 348 +/- 10 x 10(6) at [Ne-21]/g[SiO2], and suggest that the 7.1% (2 sigma) overdispersion of our measurements may be representative of the current accuracy of cosmogenic Ne-21 in quartz. CREU-1 was tied to CRONUS-A, which is a second reference material prepared from a sample of Antarctic sandstone. We propose a reference value of 320 +/- 11 x 10(6) at/g for CRONUS-A. The CREU-1 and CRONUS-A intercalibration materials may be used to improve the consistency of cosmogenic Ne-21 to the level of the analytical precision. (C) 2012 Elsevier B.V. All rights reserved.
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