MINING IN AFRICA SPECIAL — Mining important to Zimbabwean

Mining in Zimbabwe has been an important part of the economy since the 14th century, when gold mining created the wealth that built the political state of Great Zimbabwe.

With the arrival of Cecil Rhodes and the British South Africa Company in the late 1800s, gold mining became the foundation of the new British colony of Southern Rhodesia.

Since this period, about 49 million oz. gold have been declared. Based on the dimensions of the pits dug by the ancients and the grade on the floor, researchers have been able to estimate that an additional 11 million oz. may have been mined during the pre-colonial period.

The mining industry now accounts for 45% of the foreign exchange earnings in the country and employs 6% of the workforce. The country produces gold, chrome, asbestos, nickel, copper, coal and, most recently, diamonds. Recent changes in the Mining Act (1994) have allowed for “special mining leases” which allow for the repatriation of profits from new mining operations investing more than ZIM$500 million ($90 million). The mining industry has also received a great boost because of the more readily available foreign exchange to buy imported spare parts and equipment. The geology of Zimbabwe is dominated by Archaean, Proterozoic and Permian-to-Cretaceous Age rocks locally blanketed with recent Kalahari Sands. The gold deposits occur almost exclusively in the Archean age greenstone belts. Although most of the deposits are relatively small (only seven deposits with greater than 1 million oz. production), the Zimbabwe Craton has the highest gold production per square km of greenstone belt in the world. The Archean rocks also host major nickel, chrome, asbestos, lithium and tin deposits.

The 550-km-long Early Proterozoic Age Great Dyke is one of the major geological features in the world. The north-trending, layered, igneous intrusion hosts more than 50% of the world’s reserves of high-grade chrome as well as the world’s largest undeveloped platinum group metals resource. The Mid-Proterozoic Deweras sediments host Zambian copper-belt style deposits currently being mined near Chinhoyi by the Zimbabwean para-statal mining company, ZMDC. Also in the Chinhoyi region, the Proterozoic Piriwiri Black Shale hosts several small gold deposits.

The Permian-age Karoo sediments host the Hwange and Sengwa coal deposits. These two deposits represent the largest reserves of coal in sub-Saharan Africa outside of South Africa.

The potential for coal-bed methane is also being evaluated in the Karoo sediments by a local company that feels confident it will be producing methane in the near future.

The Canadian International Development Agency (CIDA) has been involved since 1983 in working with the Zimbabwe Geological Survey to improve the country’s geological infrastructure. CIDA’s major contribution is the provision of 95% aeromagnetic coverage completed in 1992.

CIDA is also involved in training the Zimbabwean workforce by assisting in the establishment of the Zimbabwe School of Mines in conjunction with Ontario’s Haileybury School of Mines. The World University Service of Canada is sponsoring a geologist to help set up the lab section for the new master of science program in mineral exploration geology that is starting this month. The newest major mining venture in Zimbabwe is the Hartley platinum mine, a joint venture between BHP Minerals (67%) and Delta Gold (33%) of Australia. The mine sits on the Great Dyke, 75 km from Harare.

The recently commissioned River Ranch diamond mine on the border with South Africa is a joint venture between Aurdiam Consolidated of Australia and Redaurum (TSE). The resource of the kimberlite pipe to a depth of 150 metres has been estimated to be 17.5 million tonnes grading 35 carats per 100 tonnes, 60% of which are gem quality.

Adding fuel to the local diamond exploration rush is that the new Venetia diamond mine of De Beers in South Africa, expected to produce 4 million carats per year at a grade of 118 carats per 100 tonnes, is only 60 km to the south.

Well established Canadian companies working in Zimbabwe are Falconbridge (TSE) and Kinross Gold (TSE). Kinross operates two gold mines, Blanket (near Gwanda) and Golden Kopjie (near Chinhoyi). Antares Gold (TSE) is also evaluating a deposit in the Gwanda area.

The Jena mine, west of Kwe Kwe, is operated as a joint venture between ZMDC and Trillion Resources (TSE).

Zimbabwe has excellent potential for an increase in mineral development in a politically stable environment.

— The author is a Canadian geologist, working at the University of Zimbabwe, who is helping to set up a new MSc program in mineral exploration geology.