Trace element homogeneity from micron-to atomic scale: Implication for the suitability of the zircon GJ-1 as a trace element reference material. Highlights The zircon reference material GJ-1 shows micron-to atomic scale chemical and structural homogeneity  GJ-1 can be used as a reference material for U-Th-Pb dating and Lu-Hf isotopic studies, but also for trace element analysis  GJ-1 combines structural and chemical homogeneity with chemical abundance and large sample size and volume  Atom probe tomography allows assessment of atomic scale chemical homogeneity of minerals e.g. reference materials Keywords zircon, reference material, trace elements, atom probe tomography, nanometre scale, GJ-1 AbstractThe quality of a chemical reference material relies on the fact that the composition of the material is homogeneous across all scales. A series of different techniques have been used to evaluate the trace element homogeneity of the GJ-1 reference zircon from the micron -to atomic scale. Cathodoluminescene imaging was conducted along with quantitative crystallographic orientation analysis and trace element analysis using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). The nanometre-scale homogeneity was evaluated by analysing five mineral tips using atom probe tomography, which provides atomic scale three dimensional chemical reconstructions with unprecedented spatial resolution. Results show that the GJ-1 reference zircon is homogeneous at all scales, both structurally and chemically. Crystallographic orientation data confirms that this gem quality zircon has no detectable internal crystallographic orientation changes such as crystalplastic deformation features or cracks. No mineral inclusions were found. Atom probe tomography shows that there is a lack of any chemical clustering or other modes of spatially defined elemental accumulation or depletion for the most abundant trace elements such as Y, Yb and Hf. This finding is supported by LA-ICPMS data revealing homogeneity within the analytical precision. Trace elements of significant abundance include P, Yb, Y, U and Hf, with contents of 30±6, 65±2, 238±5, 284±14 and 6681±57ppm, respectively. Hence, the GJ-1 zircon used as a reference zircon for U-Pb and Hf-isotopic studies is also a suitable zircon reference material for trace element analyses.

This is a repository copy of Atom probe tomography analysis of the reference zircon gj-1: An interlaboratory study.