Indigenous metallurgists made metal objects through the forging of cold and hot lumps of metal into shapes – a process known as smithing. In another process metallurgists’ poured molten metal into pre-made shaped moulds, or patterns, to make objects. Gold, copper, bronze and tin were shaped into ingots, beads and other objects by this process. There are distinguished ways and methods through which metals were worked from region to region, with other regions sharing common traits. The methods used vary from the ‘lost’ wax technique to techniques used in the work done in places like Mapungubwe.
Metallurgists, usually, have to separate the ore they want from other material in process known as extraction. Extractive metallurgy involves the process of smelting. A variety of objects were forged from the process of controlled smelting. Copper and iron, in nature, are combined with oxygen or sulphur, which must be stripped off by heat and a reducing agent – a reducing agent, in this context, is a product of nature used to strip off the material that is combined with ore, such as carbon monoxide, which is obtained by reduction or blowing air onto hot charcoal (carbon monoxide, many will know, is responsible for deaths from suffocation, because, as a reducing agent, carbon monoxide has an affinity for oxygen – simply put, and without care for technicalities, it snatches at oxygen in its vicinity (and that is what a reducing agent is) ). Gold is the only ore that occurs in nature as a metal from all the metals used in Africa and as such does not need to undergo reduction.
Indigenous metal smelting is different from the industrial methods used today. Modern smelting of iron is done in phases; the first one is that of the iron (as iron oxide) reacting at high temperatures with gaseous carbon monoxide (CO) to produce liquid iron with high Carbon content and carbon dioxide (CO2). The excess Carbon is then removed to produce different grades of steel. Soft or wrought iron would be produced in one step in pre-colonial times.
Metallurgists, in pre-colonial times, carefully watched the changes in the colour of the flames produced in the furnaces to assess in what stage, or phase, the process of, say, smelting was in. A red or yellowish flame meant there was complete combustion, which was typical of the beginning of the process. A blue flame showed the reduction process, which usually appeared towards the end of the smelting. When smelters watched the changes in flame colours this helped them to understand in what phase of the process the smelting was at.
Pre-colonial smelting used far less raw materials and labour, as opposed to modern day smelting which uses large amounts of raw materials and labour. And yet, these methods produced metal which was sufficient for local and external use for a number of centuries.
Ores and processed metals featured in trading between different parts of Africa and other continents. For example, the gold from Southern Africa was exported by Mapungubwe and Great Zimbabwe, via the Swahili trading towns of East Africa, to the Persian Gulf and the Indian sub-continent. Gold from West Africa was also traded to the Islamic Empire through the trans-Saharan caravan trade.
Importantly, pre-colonial smelting was environmental-friendly because certain tree species were preferred as charcoal. Those specific tree species were alternated to allow some species to re-grow. Smelting was only done in certain seasons and thus smelters did not need wood all the year round. All these factors allowed the forests to grow again before the next season of smelting. They are, however, examples of large-scale metallurgy that resulted in adverse effects to the environment. But, the impact of indigenous metallurgy does not have as adverse effects when compared to the large-scale damage by modern mining and metallurgy to the environment. For example, alternating tree species is an example of sustainable forest use and sorting the material while underground, as was practiced, and using waste material as backfill helps maintain waste levels on the surface as well as re-enforcing the underground structure.
Many people of this continent, such as the Chewa of Malawi, used natural draft furnaces to smelt low grade iron ores – Low grade iron ores would cost a lot to work in modern furnaces because it is expensive to build and maintain modern furnaces. Many other peoples, however, used high grade ores from either natural draft furnaces or furnaces with the aid of bellows. Smelters could produce usable iron from a wide variety of ores, ranging from what would be worthless ores today to high grade ones. And could produce sizeable objects such as copper ingots that weighed as much as 50 kilograms; from current day Democratic Republic of Congo.
Processes and techniques used in indigenous metal smithing and fabrication are varied. Some of the techniques used where applicable to a wide range of metals whilst others were only used with specific metals. Smiths chose a particular technique based on the physical properties of the metal and the technology available. For example, iron, which is solid in form, was hammered to shape while copper, which could easily be melted, was sometimes poured into a mould to produce finished products.
The process of casting involved placing of either pieces or lumps of metal into a bowl (made either of metal or ceramic) with charcoal in a hearth. The molten metal was then poured into moulds. Some of the moulds where of a permanent format, sometimes formed in the ground, whilst others where portable ones. The Venda of South Africa and the Bushongo of Congo are some of the people that used permanent templates. Portable moulds could be carved in stone and were either opened or closed. Whether the mould was opened or closed depended on the intended use or what kind of object was going to be made. Moulds were made of wet ash by the Kaonde of Zambia, clay by the Nupe of Nigeria and even steatite by the Shona at Great Zimbabwe. The designed moulds made it easy for smiths to make objects, through pouring the metal into the mould and allowing it to become solid. There is also the wax technique used in West Africa and the Sudan. The difference in the wax process compared with other casting methods was that an object was moulded first with wax or latex. The wax or latex came from the sap of trees. The whole object was made in wax or latex. It was dipped in liquid clay, and when it was dry, the mould was coated in a thick clay jacket. The mould was then fired to take away the wax or latex. In the place where the wax or latex would have been, which would be a hollow, molten metal was poured. When the molten metal had cooled, the clay outside was broken and you could then see the sculpture inside. The sculpture was then cleaned and polished.
The lost wax technique makes for sound industrialization practice. In fact, a number of industries use it as a technique to mass produce.
The Venda people of South Africa are re-known for working the copper deposits of Musina, as well as for their skill in casting copper objects known as musuku and marale. To begin with, the Venda melted small amounts of copper in ceramic crucibles and then placing the molten metal in their ground moulds. Lerale and musuku ingots were used in trade and exchange.
Bronze is an alloy, or mixture, of copper and tin. The method for working bronze was similar to that of working copper. And many objects, bronze included, were found in large numbers at archaeological sites such as Mapungubwe and Great Zimbabwe.
Tons of gold finished objects were discovered in Mapungubwe around 1933 and all date back to pre-colonial times.
The African bloomery process would make both soft iron and different grades of steel. Steel is a mixture of iron and a percentage of carbon. After the bloomery process, steel was usually improved by quenching it in water. The metal produced locally was of a high quality. Exploiters such as David Livingstone, who in his name a museum with historical artefacts in Zambia is named, in the late 1800s observed that the quality of iron produced by the Tonga of the Zambezi was of a superior quality compared to that from Europe.
Smithing in pre-colonial times used the physical properties of the metals to their advantage. And metal was very important in helping pre-colonial societies to function.
Metallurgy changed societies of sub-Saharan Africa in a number of ways. Agricultural tools were produced (It is not surprising that the use of iron has been linked with an increase in food production), spears and arrows aided people in their hunting expeditions, crafting and building was aided by tools produced from metallurgy, and many other examples one can think of including symbolic ones and beautification reasons.
The founders of most sub-Saharan states, such as Mali in West Africa, Karagwe in Tanzania, Luba and Lunda in Central Africa, Bunyoro in Uganda, Gihanga in Rwanda, and Zulu in Southern Africa, had symbolic associations with metal smiths from agriculture, trade, arsenal, etc. This is an excellent example of the link between metallurgy and the beginning of government or political organisation. The production of metals by Africans also attracted people from other regions of the world to Africa.
Metal work was instrumental in setting up local and regional trade and exchange. Iron and copper were used to trade for goods. A particular iron bar known as ‘bikie’ was used as a special currency in southern Cameroon. In Bassar, Togo, iron was traded over long distances. West Africa is full of examples of trade in metals such as the popular trade in manillas – bronze objects used as currency. There are many other examples. The working of metal allowed many people to pull resources together and form new groups or break away from existing groups to form new ones. There are modern examples such as Johannesburg where peoples from different groupings are now living together.
In southern Africa, among Phalaborwa people, copper ingots known as the musuku and lerale formed an important currency and could be exchanged for livestock, grain and other valuable produce. Metals were traded across wide regions of Africa. For example, the Katanga copper ingots, which were in the form of crosses, were traded between central Africa and regions as far south as Great Zimbabwe. Tin, which was produced at Rooiberg in South Africa, not that far off from Thabazimbi, was exchanged with states such as Great Zimbabwe and the state which came after it; based at Khami in southwestern Zimbabwe.
African pre-colonial metallurgy was also an important part of the long-distance trade that linked different parts of the continent to Europe and Asia. New states developed as late as the beginning of the second millennium, due to trade in commodities such as gold. For example, the kingdom of ancient Ghana was formed. From as late as the 15th century onwards, the Ashante of Ghana traded gold with the Portuguese, the Dutch and later the British. Mali developed as a powerful state around gold as well. Changes led to the rise of Songhai on the edges of Mali which then controlled the profitable gold trade with the Islamic empire. Colonialism ended these long-distance trade networks and set up new forms of trade.
In southern and eastern Africa, metals such as iron, gold and copper played a crucial role in the Indian Ocean trading network. This trade linked southern Africa with the Indian sub-continent and the Persian Gulf. For more than two centuries, Great Zimbabwe exported gold to the Indian Ocean and traded it for exotic products such as glass beads and porcelain. The wealth acquired was invested in huge architectural science projects such as Great Zimbabwe’s spectacular walls.
At Mapungubwe archaeologists found ceremonial iron and copper objects, together with impressive gold objects such as a sceptre, gold bowls and the famous rhino. In most parts of Africa, metallurgy also influenced the forming of relationships between societies. For example, among Abantu communities in southern Africa, iron hoes were very important for trade and as symbols in negotiating bride and marriage agreements.
There is no doubt that since their inception, indigenous mining and metallurgy have played a significant role in the development of African societies. Metallurgy promoted different social, economic and political activities in society. For example, iron was essential for making tools for agriculture and for defense. Iron spears and axes formed part of a formidable arsenal of many of Africa’s celebrated armies. Other metals such as copper, bronze and gold were mostly used for making items such as ornaments and they are complexity, strength and beauty is something that has always fascinated Africa and its people.
In the 19th century CE, Africa’s mineral wealth attracted European powers that partitioned the continent into different colonies. Clearly, one cannot understand African history without considering the role of indigenous mining and metallurgy before colonisation. More emphasis should be placed on the fact that Africa’s fortunes did change with colonialism when formerly self-sustaining miners and metallurgists were turned into a working class through the introduction of industries and wage labour. This turned previously rich people into poor workers who no longer owned any means of production as they had done in the past.
History teaches us that Africa never had any need for foreign investment, and still doesn’t. Africa needs foreign consumers!
By Themba Ka Mhlanga
Prof Shadreck Chirikure is acknowledged, special acknowledgments to my dear friend Dr Musa Manzi.