High-precision U-Pb data and reference age for Emerald Lake apatite

New isotope dilution thermal ionization mass spectrometry U-Pb data for Emerald Lake apatite demonstrate its potential as a reference material for geochronology. A three-dimensional ²³⁸U/²⁰⁶Pb-²⁰⁷Pb/²⁰⁶Pb-²⁰⁴Pb/²⁰⁶Pb isochron produces a 95.2 ± 1.1 Ma date with an initial Pb isotopic composition of ²⁰⁶Pb/²⁰⁴Pb = 18.85 ± 0.19 and ²⁰⁷Pb/²⁰⁴Pb = 15.68 ± 0.10 (n = 5, MSWD = 9.5). These data yield a weighted mean initial Pb-corrected ²⁰⁶Pb/²³⁸U date of 95.18 ± 0.10 Ma (n = 5, MSWD = 1.5) and a weighted mean initial Pb-corrected ²⁰⁷Pb/²³⁵U date of 95.20 ± 0.17 Ma (n = 5, MSWD = 0.5). The new high-precision U-Pb age of Emerald Lake apatite further enables its utility as a reference material for in situ U-Pb apatite geochronology. Aliquots of Emerald Lake apatite are available for distribution for use in future studies.