For the past 50 years, copper sourced from the Akjoujt region has been inferred primarily through the enrichment of arsenic in metal samples from archaeological sites in West Africa. However, arsenic is common to a variety of mineral deposit types and this signature was based on early low-resolution spectroscopic data. Here, we apply lead isotopic and bulk chemical analyses to copper metal and ore samples from the region of Akjoujt, in order to interrogate this signature and contribute more precise data. Our results confirm that arsenic is indeed a significantly enriched element for copper produced around at Akjoujt, but we broaden its chemical signature to include enrichment in Sn, Ni, and Co, and depletion in other chalcophile elements, but particularly depletion in Pb. Isotopically, we demonstrate that hydrothermal mineralization at Akjoujt included uranium and thorium, and produced a characteristic radiogenic lead isotopic signature dating to the late Archaean/early Proterozoic periods, in alignment with new U-Pb dating for Akjoujt. Using this signature, we analyze copper from new excavations at the Walaldé site in Senegal, which has previously been suggested as a destination for copper from Akjoujt. We show that the copper for six objects associated with a burial excavated in 2016 originates from across the Sahara and likely dates to the 1st millennium CE, as does one previously analyzed copper sample from Walaldé. We also identify three previously analyzed copper objects from the 1999 excavations at Walaldé which likely originate from Akjoujt and date to the later first millennium BCE.

In 1967 a hoard of eight X-shaped copper ingots was discovered in the village of Chombe, in central Malawi. These are all of the HXR ingot type, of which several hundred examples have been found in Zambia and Zimbabwe. They are thought to have been manufactured between the 14th and late 18th centuries CE. In 2024 we sampled five of the Chombe ingots to analyze for lead isotope analysis (LIA) and bulk ICP-MS chemical analysis at the University of Missouri Research Reactor (MURR). We conclude that all five ingots derive from the Kipushi ore body, located near Lubumbashi in the Democratic Republic of Congo (DRC). The straight-line distance between ore source and find spot is about 790 km, but we suggest that the ingots may have travelled a longer but easier route by canoe down the Kafue and Zambezi rivers, with only the last 220+ km overland to central Malawi (ca. 1200 km total). These ingots are much thinner, and therefore lighter, than typical HXR ingots, and are the only HXR ingots known so far to have been sand-cast. We infer that at some point along their journey the original ingots were recast, and discuss why this might have been done.

Published Sn isotope data along with 150 new analyses of cassiterite and four granite analyses constrain two major tin isotope fractionation steps associated with (1) separation of tin from the magma/orthomagmatic transitional environment and (2) hydrothermal activity. A distinct Sn isotope difference across deposit type, geological host rocks, and time of ore deposit formation demonstrates that the difference in the mean δ124Sn value represents the operation of a unified process. The lower Sn isotope values present in both residual igneous rocks and pegmatite suggest that heavier Sn isotopes were extracted from the system during orthomagmatic fluid separation, likely by F ligands with Sn. Rayleigh distillation models this first F ligand-induced fractionation. The subsequent development of the hydrothermal system is characterized by heavier Sn isotope composition proximal to the intrusion, which persists in spite of Sn isotope fractionating towards isotopically lighter Sn during hydrothermal evolution.

Lead isotopic analysis (LIA) has become a powerful tool in archaeology for identifying the geological source, or provenance, of non-ferrous metals and their alloys. Most applications have historically focused on Europe, but there is also a long, and rapidly expanding, history of LIA application to the archaeological record of Africa. Here we highlight how Africanist archaeologists can apply LIA to understand materials provenance and circulation, and we discuss why this technique works well in Central and southern Africa but requires a more nuanced approach for applications in North, West, and East Africa.

Tin is a much rarer element (2.3 ppm in the earth’s crust) than copper (68 ppm), so in most regions, bronze can only be made with tin obtained from far away. In this paper, we investigate the sources of tin in 153 tin and bronze samples from southern Africa, dated between 1200 and 1800 CE, by integrating lead isotope, tin isotope, and trace element measurements. Our data show that tin from the prehistoric tin mines at Rooiberg (South Africa) was transported more than 900 km. We also present evidence of tin production from other sources, likely pegmatites, within the Bushveld Large Igneous Province of South Africa. Although many of the bronzes analyzed are from archaeological sites in present Zimbabwe, we have found no definite evidence so far for exploitation of tin sources within Zimbabwe.

Ingombe Ilede is located just north of the Zambezi River, and has often been seen as a trading station connected to Central Africa, the Zimbabwe Plateau and the Indian Ocean. Discussion of the richly appointed burials in its Central Cemetery has been hindered by uncertainty over their ages. In this article, we report four new radiocarbon dates from Ingombe Ilede and six new dates from sites in northern Zimbabwe that are relevant to a wider understanding of Ingombe Ilede and its connections. These ten dates are all on organic fiber cores within copper and bronze jewelry, for which we also report chemical compositions, lead isotope ratios, and (for bronzes) tin isotopic ratios. We show that the richer burials in the Central Cemetery were interred no earlier than the mid fifteenth century. By this time copper from the Central African Copperbelt, 500–700 km north of the Zambezi, had been transported into northern Zimbabwe for at least two centuries, as had tin from the Bushveld Large Igneous Province (BLIP) 900–1000 km south of the Zambezi. The rich burials at Ingombe Ilede represent a late phase of a longstanding trade in copper from the Copperbelt to the Zimbabwean plateau.

Research on Southern Africa between ca. 500 CE and ca. 1500 CE has been dominated by tracing the connection of the subcontinent to the maritime trade across the Indian Ocean. But until recently, the lack of effective tools to reconstruct precolonial movements of commodities made it appear as if Africa, despite its vast size, lacked internal long-distance exchange. We challenge this assumption by combining oral historical with archaeological and scientific data to identify long-distance internal African commodity exchange and associated variable networks of distribution. We identify long-distance exchange of commodities, such as iron hoes, copper ingots and ostrich eggshell beads that are fulfilled, as mediated by different cosmologies, quotidian and luxury desires in ancient southern and Central Africa. We conclude that precolonial Southern Africa was deeply interconnected through networks of production and exchange and that entanglements with the Indian Ocean provided optional commodities to complement the pre-existing and the locally available.

Glass beads first appear in the archaeological record of southern Africa around the mid-first millennium CE, marking the earliest signatures of extensive connections between the southern African region, the East African coast, and the broader Indian Ocean rim. Key research focused on glass beads, particularly from notable southern African polities, like the renowned Mapungubwe and Great Zimbabwe sites, has laid the groundwork for a regional taxonomic series of these beads, emphasizing their role as indicators of wealth and social status. This paper introduces new data on 59 glass beads from a recently excavated and lesser-known Zimbabwe culture site in the Mberengwa region of south-central Zimbabwe. The analysis employs non-invasive techniques, including typological classification and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). The investigation identifies six glass bead series from Chumnungwa, composed of plant ash-lime (v-Na-Ca), vegetable soda-high alumina (v-Na-Al), and soda-based glasses with high-alumina concentrations (m-Na-Al). These beads, widely distributed in Asia and Africa between the eight and seventeenth centuries, shed new light on the geochemistry, provenance, and circulation patterns of glass beads in southern Africa, particularly within a community situated beyond the well-known Iron Age polities. Notably, Chumnungwa emerges as the first known Zimbabwe culture site in southern Africa to yield m-Na-Al 6 glass beads. However, as recently demonstrated at the Toutswe sites in Botswana, it is probable that other Zimbabwe culture sites in the region also possessed m-Na-Al 6 glass beads. These beads may have been misclassified as m-Na-Al 2 glass since this group was only recently unveiled on the East African coast, after the bulk of the currently available literature had been published. Insights drawn from contextual recovery data and Shona anthropology form the basis for an extended discussion on the consumption and sociality of glass beads in Iron Age southern Africa. Ultimately, the study underscores the challenge of typologically categorizing beads into established series without the application of LA-ICP-MS and other scientific approaches.

Rectangular, fishtail and croisette copper ingots have been found in many locations in Central and southern Africa where excavated samples date to between the fifth and eighteenth centuries cal. AD. For more than fifty years, scholars have debated whether these ingots were all made in the Central African Copperbelt, where there are many finds of matching moulds, or if moulds found in Zimbabwe show that copies were produced locally. Lead isotopic and chemical analyses have recently confirmed that the Copperbelt supplied copper ingots to both southern Congo-Kinshasa and the Zimbabwe Plateau between the ninth and eighteenth centuries, but that one HXR ingot can tentatively be sourced to the Magondi Belt copper deposits in northern Zimbabwe. We expand this discussion here by linking ingot chemistry and isotopic provenance with distribution patterns and ingot morphologies. The combined evidence suggests that groups making Luangwa Tradition pottery were responsible for transporting HIH and HXR ingots, and the technological styles for making them, far to the south of the Copperbelt. These croisette ingots link constellations of practice in the Copperbelt and Zimbabwe, possibly through the movement of specialised traders and metalworkers. We identify some of the individuals buried at Ingombe Ilede and Chumnungwa as possible examples of these specialists.

The broad spatial distribution and long period of production of Rio Grande Glaze Ware vessels hides considerable material diversity within the typological grouping as a ware. This has long made archaeometric techniques attractive options for understanding variability within the Rio Grande Glaze Ware category. We present the results of new petrographic analysis of Rio Grande Glaze Ware pastes and new isotopic analysis of Rio Grande Glaze Ware glaze paint. The results of these new analyses complement extensive earlier work characterizing both Rio Grande Glaze Ware pastes and paint. Especially relevant is the identification of glaze paints made primarily with lead ores from the Hansonburg district or made by mixing Hansonburg ore with the more commonly used Cerrillos district ores. The predominant use of Cerrillos ore in the production of lead glaze paint identified in prior work is nuanced through the additional data presented here, which suggests a division in networks of lead ore and/or glaze paint procurement between a larger, northern network making use of Cerrillos ores, and a smaller, southern network relying on Hansonburg ores for glaze paint production.

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.

Recent analytical developments in the field of mass spectrometry have made possible accurate measurements of “non-traditional” isotopic ratios of elements such as Fe, Cu, Ag, Sn, Sb and Hg. The stable isotopes of these elements do not have any radioactive parents, but their ratios undergo limited fractionation from various causes, most of them mass-dependent. These effects can lead to variation in isotopic ratios of natural materials (minerals, rocks, ores, etc.) and in archaeological artifacts derived from them. Research since 2010 has investigated whether variation in these isotopic ratios can be used to infer the geological provenance of archaeological materials, including bronze and glass. Here we review recent research on these isotopic systems in archaeology, their principal applications, as well as expected future developments in their use. We conclude that none of these isotopic systems are likely to be very useful for provenance, mostly because of limited ranges of isotopic ratios and/or extensive overlap between the isotopic ratios of most geological sources. Copper isotope ratios are however a reliable method for inferring the type of ore (supergene versus hypogene) smelted to produce copper, and recent studies indicate that silver isotope ratios can also be applied to this effect.

The first part of this paper is a brief critical history of the use of Pb isotopes for inferring the geological provenance of archaeological materials, with an emphasis on non-ferrous metals. The second part examines variation in the Pb isotopic ratios of oxide and sulphide ore minerals in selected regions of the world, and relates these to the geological histories of ore formation in each region. This exercise shows that in regions where most ore deposits are of similar geological age-as in the Andes, Europe and the circum-Mediterranean-provenance analysis with Pb isotopes is inherently difficult because geographically distant sources often exhibit similar isotopic ratios. Conversely, regions with many periods of ore formation-such as southern Africa-appear to be very promising regions for future studies of provenance with Pb isotopes. The wider implication of this exploratory survey is that archaeologists should carefully consider the range and clustering of geological Pb isotopic ratios in their regions of interest before investing large sums of money into Pb isotopic analysis of artefacts.

Copper was highly valued in sub-Saharan Africa for jewellery and as a store of wealth, but was rarely used for tools or weapons. The Central African Copperbelt is one of the world's largest copper deposits, and is known to have been mined since at least 400-600 cal CE, but has seen very little archaeological investigation. We measured lead isotope ratios and trace element concentrations in 20 copper objects, dating between ca. 650 cal CE and ca. 1200 cal CE, from two sites in the Tsodilo Hills in northwestern Botswana. The results show unequivocally that almost all derive from Copperbelt ore deposits in Katanga Province, Democratic Republic of the Congo, at least 1050 km from Tsodilo. Our results are very similar to those recently obtained for a suite of 45 copper ingots, dated between 9th and 18th centuries cal CE, most of which are from cemeteries in the Upemba Depression, about 200 km north of the Copperbelt (Rademakers et al., 2019).

Decorative, polychrome ceramics from Corinth, Greece, produced during the 8th-6th centuries B.C.E. were luxury goods widely traded throughout Greece and the Mediterranean. Corinthian pottery is the first 5-color polychrome ceramic technology, having slip-glazes in distinctive white, black, red, yellow, and purple colors, and in a variety of surface finishes from glossy, to semi-matte, to matte. The firing temperature range, 925-1075°C, was determined experimentally to be to be higher than previously reported, similar to the Corinthian amphorae and other ceramic products. This firing range is higher than that of the better known, more prestigious Athenian Black-figure and Red-figure ceramics. In this study three examples of Corinthian and one example of Athenian Black-figure ceramics from the Marie Farnsworth collection at the University of Arizona were tested and compared to thirteen clays from Corinth. Analytical techniques included Fourier-transform infrared spectroscopy (FTIR), scanning-electron microscopy with energy-dispersive spectroscopy (SEM-EDS), micro-Raman spectroscopy, and wavelength-dispersive electron microprobe (EPMA with BSE-SEM). Artisans in Corinthian workshops experimented to change the colors of the slips by varying the type and amount of iron-rich raw material, as well as the composition of the clay used as a binder and the amount of flux used as a sintering aid to promote glass formation. Corinthian artisans developed not only different recipes to produce the various colors, but also they were able to control raw-material particle size and composition to produce variations in surface luster (matte, semi-matte and glossy). This research suggests that Corinthian polychrome-slip technology was based on careful control of particle processing, of compositional control of raw materials and their admixtures, and of firing temperature. The behavior or practice of adding different ratios of pigments and glass-forming fluxes to form various optical effects implies a detailed knowledge of what happens when these are heated and fired. This is a process of experimentation focused on developing a distinctive craft practice, which produced a distinctive and highly valued material. The Corinthians developed a more complex, easily recognizable, and culturally distinctive ceramic technology that was intentionally established as a cultural brand, and probably as a luxury brand of high socio-economic value. This research deepens our understanding of the complex pigment processing and firing technologies employed in the production of Corinthian ceramics.