Nickel Isotope Variations in Terrestrial Silicate Rocks and Geological Reference Materials Measured by <scp>MC</scp>‐<scp>ICP</scp>‐<scp>MS</scp>

<jats:p>Although initial studies have demonstrated the applicability of <jats:styled-content style="fixed-case">N</jats:styled-content>i isotopes for cosmochemistry and as a potential biosignature, the <jats:styled-content style="fixed-case">N</jats:styled-content>i isotope composition of terrestrial igneous and sedimentary rocks, and ore deposits remains poorly known. Our contribution is fourfold: (a) to detail an analytical procedure for <jats:styled-content style="fixed-case">N</jats:styled-content>i isotope determination, (b) to determine the <jats:styled-content style="fixed-case">N</jats:styled-content>i isotope composition of various geological reference materials, (c) to assess the isotope composition of the <jats:styled-content style="fixed-case">B</jats:styled-content>ulk <jats:styled-content style="fixed-case">S</jats:styled-content>ilicate <jats:styled-content style="fixed-case">E</jats:styled-content>arth relative to the <jats:styled-content style="fixed-case">N</jats:styled-content>i isotope reference material <jats:styled-content style="fixed-case">NIST SRM</jats:styled-content> 986 and (d) to report the range of mass‐dependent <jats:styled-content style="fixed-case">N</jats:styled-content>i isotope fractionations in magmatic rocks and ore deposits. After purification through a two‐stage chromatography procedure, <jats:styled-content style="fixed-case">N</jats:styled-content>i isotope ratios were measured by <jats:styled-content style="fixed-case">MC</jats:styled-content>‐<jats:styled-content style="fixed-case">ICP</jats:styled-content>‐<jats:styled-content style="fixed-case">MS</jats:styled-content> and were corrected for instrumental mass bias using a double‐spike correction method. Measurement precision (two standard error of the mean) was between 0.02 and 0.04‰, and intermediate measurement precision for <jats:styled-content style="fixed-case">NIST SRM</jats:styled-content> 986 was 0.05‰ (2<jats:italic>s</jats:italic>). Igneous‐ and mantle‐derived rocks displayed a restricted range of δ<jats:sup>60/58</jats:sup><jats:styled-content style="fixed-case">N</jats:styled-content>i values between −0.13 and +0.16‰, suggesting an average <jats:styled-content style="fixed-case">BSE</jats:styled-content> composition of +0.05‰. Manganese nodules (Nod A1; P1), shale (<jats:styled-content style="fixed-case">SDO</jats:styled-content>‐1), coal (<jats:styled-content style="fixed-case">CLB</jats:styled-content>‐1) and a metal‐contaminated soil (<jats:styled-content style="fixed-case">NIST SRM</jats:styled-content> 2711) showed positive values ranging between +0.14 and +1.06‰, whereas komatiite‐hosted <jats:styled-content style="fixed-case">N</jats:styled-content>i‐rich sulfides varied from −0.10 to −1.03‰.</jats:p>