Magnesium Isotopic Compositions of International Geological Reference Materials.

Magnesium isotopic compositions are reported for twenty-four international geological reference materials including igneous, metamorphic and sedimentary rocks, as well as phlogopite and serpentine minerals. The long-term reproducibility of Mg isotopic determination, based on 4-year analyses of olivine and seawater samples, was ≤ 0.07‰ (2 s) for δ26Mg and ≤ 0.05‰ (2 s) for δ25Mg. Accuracy was tested by analysis of synthetic reference materials down to the quoted long-term reproducibility. This comprehensive dataset, plus seawater data produced in the same laboratory, serves as a reference for quality assurance and inter-laboratory comparison of high-precision Mg isotopic data. [ABSTRACT FROM AUTHOR]