Iron ores were worked as early as middle stone age times in Swaziland for use as pigments. It is clear that body pigments and iron oxides ochres for body pigments and later for decorating rock surfaces were eagerly sought after from early stone age times. A piece of haematitic colouring matter was even brought into the Olduvai Basin by very early stone age tool-users.
By late stone age times manganese, spéculante, and haematite were being regularly mined at localities in Zambia, Swaziland and in the northern Cape. An excavation in some of the workings at Doornfontein indicated regular mining operations involving galleries and chambers from which up to 45 ooo metric tons of specularite may have been obtained, probably by Khoisan-speaking groups from the ninth century of our era onwards. It is
likely that the existence of such mines and the implied knowledge of metallic ores and their properties helped the rapid growth of an iron technology in the first half of the first millennium of our era.
Elsewhere in sub-Saharan Africa we do not have such clear indications of mining for iron and it seems that the lateritic crust of the tropical areas was the most likely source of iron ores. Bog iron, however, was used in the lower Casamance valley in Senegal and at Machili in Zambia.
The iron so obtained would have been broken down into very small pieces and hand-selected for smelting. A region where the mining, as opposed to the surface collecting, of latérites may have been undertaken was to the north of the Gambia river in the area of the Senegambian megaliths, which are themselves upright blocks of latérite. Their use there as ritual structures and the growth of an iron technology in the area during the first millennium of our era would indicate that it would be a small step towards the actual mining of the latérites for smelting. It is possible that extensive smelting of the latérites was an essential preliminary to the idea of quarrying the latérite for building purposes.
A similar process may have developed in the Central African Republic where megaliths also occur. It has been suggested by Wai Andah in Chapter 24 that the ease of Iaterite digging as opposed to haematite-quarrying may be one of the clues to a hitherto unsubstantiated claim for an indigenous development of an iron technology in Africa.
Latérite, when damp and buried beneath a soil profile, is relatively crumbly and far easier to dig through than normal rock. Unfortunately, except for the southern African mines, no other certain iron-‘mining’ areas have been either found or accurately dated. It is possible that the Uelian stone axes of haematite in north-eastern Zaïre and Uganda may be of iron age date and fashioned in haematite in imitation of wrought iron.
Author: M.Posnansky. Historian and archaeologist; author of a number of important works on the archaeological history of East Africa.
Source: General History of Africa Vol.II. [Editor: G.Mokhtar] Ancient Civilisations of Africa. Chapter 29.The societies of Africa south of the Sahara in the early iron age.