School of Anthropology, University of Arizona, Tucson, AZ, United States of America.
Archaeometry Laboratory, Research Reactor Center, University of Missouri, Columbia, MO, United States of America.
PLoS One. 2023 Mar 22;18(3):e0282660. doi: 10.1371/journal.pone.0282660. eCollection 2023.
The southern third of Africa is unusually rich in copper ore deposits. These were exploited by precolonial populations to manufacture wound-wire bangles, other forms of jewelry, and large copper ingots that were used as stores of copper or as forms of prestige. Rectangular, fishtail, and croisette ingots dating between the 5th and 20th centuries CE have been found in many locations in the Democratic Republic of the Congo (DRC), Zambia, and Zimbabwe, with isolated finds in Malawi and Mozambique. Molds for casting these ingots have been found mostly in the Central African Copperbelt, but also around the Magondi Belt copper deposits in northern Zimbabwe. For years, scholars have debated whether these ingots were exclusively made in the Copperbelt or if the molds found in Zimbabwe indicate that local copies were produced from Magondi Belt copper ore (Garlake 1970; Bisson 1976). Before the recent application of lead isotopic and chemical methods to provenance copper in central and southern Africa, there was no way to discern between these hypotheses. Rademakers et al. (2019) and Stephens et al. (2020) showed that copper artifacts from southern DRC (mostly from Upemba) and from northwestern Botswana (Tsodilo Hills) match the lead isotope ratios of ores from the Copperbelt. Building upon these previous studies, we present here the first results from a copper provenance project across the southern third of Africa, from the Copperbelt to northern South Africa. We apply lead isotopic analysis (LIA) and chemical analyses to establish the provenance of 29 croisette ingots recovered in Zimbabwe, 2 fishtail and 1 rectangular ingot recovered from sites in Zambia, and an "X" shaped ingot smelted in an experiment in Zambia in the 1970's. Our chemistry and lead isotopic results indicate that 16 of these objects were smelted with copper from the Copperbelt, 16 objects source more specifically to the Kipushi deposit within this geological district, and only one HXR ingot sources to the Magondi Belt in Zimbabwe. Taken together, we clearly illustrate that croisette ingots were traveling significant distances to reach their eventual sites of deposition, and that there was also local production of these objects in Zimbabwe.
非洲南部地区异常富含铜矿。这些矿床在殖民前时期被人们开采，用于制造线纹手镯、其他形式的珠宝以及大型铜锭，这些铜锭被用作铜的储存或作为威望的象征。在刚果民主共和国（DRC）、赞比亚和津巴布韦的许多地方都发现了可追溯到公元 5 世纪至 20 世纪的矩形、鱼尾形和十字形铜锭，在马拉维和莫桑比克也有孤立的发现。用于铸造这些锭的模具主要在中非铜带发现，但也在津巴布韦北部 Magondi 带铜矿周围发现。多年来，学者们一直在争论这些锭是否仅在铜带制造，或者在津巴布韦发现的模具是否表明当地从 Magondi 带铜矿石中生产了复制品（Garlake 1970；Bisson 1976）。在最近应用铅同位素和化学方法研究中非和南非南部的铜矿来源之前，无法辨别这些假设。Rademakers 等人（2019 年）和 Stephens 等人（2020 年）表明，来自刚果民主共和国南部（主要来自 Upemba）和博茨瓦纳西北部（Tsodilo 山）的铜制品与铜带矿石的铅同位素比值相匹配。在这些先前研究的基础上，我们在此介绍了一个横跨非洲南部地区的铜产地项目的首批结果，从铜带到南非北部。我们应用铅同位素分析（LIA）和化学分析来确定在津巴布韦回收的 29 个十字形锭、在赞比亚回收的 2 个鱼尾形和 1 个矩形锭以及 1970 年代在赞比亚进行的实验中熔炼的“X”形锭的产地。我们的化学和铅同位素结果表明，其中 16 个物体是用铜带的铜熔炼的，16 个物体更具体地来源于该地质区的 Kipushi 矿床，只有一个 HXR 锭来源于津巴布韦的 Magondi 带。综上所述，我们清楚地表明，十字形锭需要经过很长的距离才能到达最终的沉积地点，并且在津巴布韦也有这些物体的本地生产。
