Was silver coinage minted from fresh metal newly extracted from the mine or was it from recycled silver deriving from older coins, silverware, or cult objects? The answer helps understand the provenance of coins and their circulation. Using Pb isotopes, the present work proposes a method to disentangle the sources of 368 silver-alloy coins from Athens, Corinth, Aegina, Thasos, Thrace, Macedonia, and Ptolemaic Egypt. We outline a new mixing model based on Principal Component Analysis and allowing for multiple steps of bullion recycling. The first component accounts for 94–99% (typically 97–99%) of the total variance, which indicates that the data form a well-defined alignment indicative of a nearly binary mixture between two source ores referred to as ‘end-members’. Isotopic evidence establishes the subordinate but pervasive practice of remelting. The strong skewness of the first principal component distribution shows that lead is dominated by the binary mixing of end-members. The geologically young end-member has high ²⁰⁶Pb/²⁰⁴Pb and is best exemplified by Laurion ore used in Athenian coinage. With the possible exception of Ptolemaic samples, the second end-member attests to the persistence of a low-²⁰⁶Pb/²⁰⁴Pb, geologically much older, end-member. In most cases, the distributions of a further two principal components are nearly symmetric and can be considered normal. If they represent ore sources, their very small contribution to the total variance qualifies them as ‘noise’ (caused by random isotopic fluctuations in the ores and analytical issues). We find that the Pb isotope ratios in the coinage issued by each minting authority are distributed as a power law. The slope of this distribution varies from one mint to another, with the steepest slopes (Corinth and Ptolemaic Egypt) indicating the predominance of freshly mined silver. The shallow slope of Macedonia demands a larger proportion of geologically old Pb. Silver supplied to the mint of Athens shifted from a mixture of high- and low-²⁰⁶Pb/²⁰⁴Pb in the late 6th c. BCE to a predominance of unmixed high-²⁰⁶Pb/²⁰⁴Pb ore from the mines of Laurion thereafter and fell back to a mixture with intermediate Pb isotope compositions in the second half of the 4th c. BCE. The limitation of the present study resides in the relatively small number of Pb isotope data for each mint, which, in most cases, prevents a statistically significant analysis of these data by periods. Nevertheless, the quasi-binary nature of most silver mixes stands out as a new and strong first-order, albeit somewhat counterintuitive, inference from the present data.

银币是用新从矿井中提取的新鲜金属铸造的，还是用从旧硬币、银器或邪教物品中回收的银来铸造的？答案有助于了解硬币的来源及其流通。目前的工作提出了一种方法，利用铅同位素来解开来自雅典、科林斯、埃伊纳、萨索斯、色雷斯、马其顿和托勒密埃及的 368 枚银合金硬币的来源。我们概述了一种基于主成分分析的新混合模型，并允许金银回收的多个步骤。第一个组成部分占总方差的 94–99%（通常为 97–99%），这表明数据形成了明确的对齐方式，表明两种源矿石（称为“最终成员”）之间几乎是二元混合物。同位素证据证实了重熔的次要但普遍的做法。第一主成分分布的强偏度表明铅主要由端元的二元混合主导。地质上年轻的端元具有较高的²⁰⁶ Pb/ ²⁰⁴ Pb 含量，雅典铸币中使用的劳里昂矿石就是最好的例子。除了托勒密样本之外，第二个端元证明了低²⁰⁶ Pb/ ²⁰⁴ Pb 的持续存在，其地质年代要古老得多。在大多数情况下，另外两个主成分的分布几乎是对称的并且可以被认为是正态的。如果它们代表矿石来源，则它们对总方差的贡献非常小，因此将它们视为“噪声”（由矿石中的随机同位素波动和分析问题引起）。我们发现每个造币机构发行的硬币中的铅同位素比率呈幂律分布。这种分布的斜率因铸币厂而异，其中最陡的斜率（科林斯和托勒密埃及）表明新开采的白银占主导地位。马其顿的浅坡需要更大比例的地质古老的铅。6 世纪末，供应给雅典造币厂的白银从高²⁰⁶ Pb/ ^{204 Pb 的混合物转变为低 206 Pb/ 204 Pb 的混合物。}公元前，劳里恩矿区以未混合的高²⁰⁶ Pb/ ²⁰⁴ Pb 矿石为主，并在 4 世纪下半叶回落到具有中间 Pb 同位素组成的混合物。公元前。本研究的局限性在于每个薄荷糖的铅同位素数据数量相对较少，在大多数情况下，这阻碍了按时期对这些数据进行统计上显着的分析。然而，大多数白银混合物的准二元性质从现有数据中脱颖而出，成为一种新的、强有力的一阶推论，尽管有些违反直觉。