The isotopic composition of lead often varies from one source of common copper ore to another ， with variations exceeding the measurement error ； and preliminary studies indicate virtually uniform is topic composition of the lead from a single copper - ore source 铅的同位素构成经常在一种普通铜矿石来源与另一种铜矿石来源之间存在差异，其差异程度超出测量误差；而最初的研究表明，对于来自单独一个铜矿石来源的铅来说，其同位素构成几乎是毫无二致的。
