Hunting for the origins of the ‘red gold’ in African antiquity
The coppersmiths of ancient Zimbabwe sourced their ore from the same mineral-rich belts in sub-Saharan Africa that supply today’s mining industry. Modern isotope technology is allowing archaeologists to trace the precise locations of the ores they smelted and mixed, showing a complex trading network and technological exchange across the region, with Great Zimbabwe the economic engine room at the centre of it.
Written by: Leonie Joubert
Photographs by: Sam Reinders
Bedone Mugabe is a child of Great Zimbabwe, so it’s hardly a surprise that the 32-year-old archaeologist is sifting through its relics to uncover the secrets to his ancestors’ copper smelting practices to learn more about how the capital fitted into sub-Saharan Africa’s complex trade and technology exchange routes at its peak during the late Iron Age.
Mugabe’s father Daniel is a stone mason whose career has been spent restoring the ruins’ walls using the same craft that’s been handed down through generations of Shona masons.
‘As a young kid, I would go along with my dad to work, and watch him reconstruct these walls,’ says the grinning doctoral student from his office in the Department of Archaeology at the University of Cape Town (UCT).
‘I was fascinated by how these people could build such a massive site without the use of mortar.’
His father is approaching retirement after a lifetime in service to restoring similar sites around the region and training others in the craft that can’t be learned at a university.
Now the younger Mugabe is taking on the mantle from his father, although this wasn’t the path Daniel hoped for him.
‘Because dad works in ancient architecture, he was against the idea of me doing anything related to that,’ Mugabe says.
Daniel’s plan was for his son to study something like rural and urban development and planning. But the pull of archaeology was irresistible for this youngster, whose family line had lived within the confines of this historic site for generations.
It was the metallurgical relics at the site that most intrigue Mugabe, and the isotopic fingerprints held inside the mixed metals found here that are allowing him to fill gaps in the archaeological knowledge base about where the copper smiths of the Kingdom of Zimbabwe sourced the ores and mixed alloys between 1,000 and 1,700 CE.
Trading metal and metal-working technologies in African antiquity
Copper is known as the ‘red gold’ of Iron Age Africa. It was a prized metal, with economic, social, cultural and practical value. It was traded as a form of currency, and as a good itself.
Its malleability made it ideal for crafting tools and jewellery and making weapons. Its relative scarcity pushed up its value, too, which contributed to it becoming a symbol of wealth and social status across pre-Colonial sub-Saharan Africa.
There are many kinds of metals and alloy artefacts found in and around Great Zimbabwe, including iron, gold, bronze, copper, lead, tin and brass. These are testimony not only to the extensive trade routes that the kingdom was connected to, but the sophistication of the metal workers’ skill and expertise in transforming ores into metals and blending metals to create different alloys.
There were many gaps in the archaeological record, though, in terms of understanding the origin of copper- based metals and ores, as well as how the technologies to work them got here.
Indigenous peoples invented their iron age technologies, today’s archaeologists are beginning to agree, and the young Mugabe wanted to answer some of these questions.
‘Where were these metals coming from? Where were the mining and metal working technologies coming from, and how did they get here? Did it come from the Phoenicians, or the Chinese, or Indian and Arabian traders? Were my ancestors interacting with people from the coast?’
When he began is master’s in archaeology at UCT, he decided it was time to fill in some of these gaps.
‘Scientifically, little is known about the nature and extent of the copper-based metal economy and circulation at Great Zimbabwe and other complex societies or kingdoms near to Great Zimbabwe at the time,’ explains Mugabe.
Traditional archaeology limited copper sources to well-known and geochemically researched mining areas such as the Copper Belt region in Zambia and the Democratic Republic of Congo (DRC), and Phalaborwa in present-day South Africa. Archaeologists also believed that copper and alloy metal working technology and knowledge came to Great Zimbabwe from metallurgist experts at the coast.
Mugabe didn’t buy it: the extent to which copper-based artefacts occur at Great Zimbabwe suggests that these metals were being mined more widely across the region, and that metallurgists here learned the skills themselves. He wanted to put this idea to the test.
For his master’s research, he collected 26 wound wire jewellery, such as bangles, anklets and necklaces, which were found at the Hill Complex at Great Zimbabwe. He looked at the chemical and isotopic makeup of each of these.
These samples were analysed at the University of Cape Town, in the materials laboratory in the Department of Archaeology, at the university’s Electron Microscopy Unit, and at the Multi-Collector-ICP MS Facility in the Department of Geology.
The modern mining industry has provided an extensive map of Africa’s mineral deposits, including the isotopic distribution of its ores.
‘By comparing the chemistry and isotope information in the copper artefacts from Great Zimbabwe with the current geological database of southern Africa, the archaeology, archival data and maps, I was able to track the ores’ probable and likely origin to specific regions and deposits,’ he says, ‘such as the Copper Belt in Zambia and DRC , the Empress Mafic and Magondi belt in Zimbabwe, and Limpopo and Phalaborwa deposits in present-day South Africa.’
‘This suggests that Great Zimbabwe participated directly and indirectly in the vibrant micro, regional and interregional circulation of copper and other resources,’ Mugabe concludes.
Now, with his doctoral work, Mugabe is zooming in even closer.
Archaeological questions that copper isotope studies have yet to help answer
Namakwaland is a long way from the Great Zimbabwe site. Today, it’ll take nearly 24 hours to drive the 2,000km distance from the ruins, which are just east of the modern-day city of Bulawayo, to this semi-desert region near the West Coast of modern-day South Africa and Namibia.
At the height of the kingdom — from about 11th to 15th Centuries — it would have taken months to ship metal ores from mining sites in Namakwaland, to the economic and political hub of Great Zimbabwe.
But archaeologists don’t yet know if Namakwaland was a source of copper for the kingdom, even though it was an abundant metal back then and abundant today. By using similar analysis to those done by Mugabe, it would be possible for archaeologists to identify if the greenbelt deposit here has the same distinctive isotopic markers as those found in the copper and copper alloy artefacts at Great Zimbabwe.
When the Kingdom of Zimbabwe was at its peak during the late Iron Age, mining prospectors in Namakwaland might have scoured the surface of the ground for telltale signs of copper deposits, just as they are known to have done in places like the Limpopo mobile belt, the northern lowveld in SA, and the Hurungwe area in Zimbabwe, amongst others. The distinctive greenish seams in rocky outcrops hinting, or malachite crystals, would have jumped out at any attentive traveller in these parts.
The relationship between Great Zimbabwe and Namakwaland’s minerals is still a bit contested, says Mugabe. However, developing a new analytical protocol and application of copper isotope analysis here in southern Africa will help archaeologists here answer the question themselves, without having to send samples abroad or rely on international experts.
‘We do have evidence that copper from Great Zimbabwe came from Phalaborwa Igneous Complex, and that tin came from Rooiberg tin mine in the southern Waterberg, about a hundred kilometres north-west of present-day Tshwane,’ says Mugabe. ‘If Namaqualand copper was already in circulation in the region, then is it possible that it might have reached Great Zimbabwe.
Back then, metals from the Copper Belt or Phalaborwa would have taken months or even years to cross the region. Most likely, societal elites at Great Zimbabwe — subjects within the state, as well as independent communities that lived in areas rich in copper or tin ore — would have exchanged copper ore such as malachite, or finished goods, either directly or indirectly in the form of gifts, tributes or even marriage alliances.