In the 1980s the Canadian mining industry began a process of global expansion, transforming into a world-leading industry that tapped into mineral resources on virtually every continent. Many scholars associate this development with the economic changes brought about by Structural Adjustment, which opened large swathes of the planet to foreign investment, but there is a much longer history of Canadian mining abroad. This thesis explores the Imperial roots of the mining industry through an analysis of a lesser-known mining project undertaken by a McGill geologist in the late 1930s, the much-mythologized Williamson Diamond Mine of Tanzania. The Williamson Diamond Mine provided invaluable industrial material during the Second World War, eventually becoming one of the most technologically advanced schemes in British Africa. The mine hosted a unique community of Canadian and European experts tasked with operating that technology while supervising the much larger African workforce, a situation reflected in the segregated, racial division of labor and associated investment in security of the mine, which still haunts contemporary Canadian mining projects. By locating the origins of Canada’s global mining industry in colonial Africa —and the life trajectory of Williamson himself —this thesis also aims to draw attention to the unstable yet durable transnational connections that linked different sites within the British Empire, Canada and Tanzania, through decolonization and past the Cold War period. In the process, this work sets out to make a contribution to Canadian Global History that highlights the importance of further study into Canada-Africa relations.