Chalcopyrite from the Xiaotongchang Cu Deposit: A New Sulfide Reference Material for Low‐Level Re‐Os Geochronology

As the application of the rhenium–osmium (Re‐Os) chronometer in low‐level (low Re mass fraction) sulfides becomes more popular, there is increasingly a need for a corresponding reference material for analytical quality control. This study presents a new low‐level, highly radiogenic chalcopyrite reference material for Re‐Os geochronology. Chalcopyrite was acquired from the Xiaotongchang (XTC) copper deposit in Yun’nan Province, China. Homogeneity tests were used by performing Re‐Os analyses on eleven randomly selected aliquots of powdered chalcopyrite using ICP‐MS. We also performed stability tests on four bottles of powdered chalcopyrite samples over a period of 36 months. The results from analysis of variance and Student’s t ‐test indicated that the XTC sample was homogeneous with respect to Re, 187 Os mass fractions and model age. Three laboratories participated in an inter‐laboratory comparison scheme for certification, performed using N‐TIMS and MC‐ICP‐MS, and employing two different spiking techniques. The reported values for model ages obtained for the XTC chalcopyrite in this study resulted in an age RM value of 229.3 ± 3.7 Ma at the 95% confidence level (95% conf.). Additionally, Re and 187 Os mass fractions of 26.5 ± 1.9 ng g −1 and 63.7 ± 4.7 pg g −1 (95% conf.), respectively, are also reported, providing further information values.