Possible consequences of continuing internal political unrest and the imposition of foreign sanctions raise concerns about the traditional reliability of the Republic of South Africa (South Africa) as a major world supplier of important minerals. A recent Bureau of Mines technical report (Open File Report 76-86) examined the impact of temporary peacetime disruption scenarios for six key materials (chromium, cobalt, gold, manganese, platinum-group metals, and vanadium) and mitigating options. Because of South Africa's dominant producer position for these minerals (except for cobalt), expansion of primary production capacity outside of South Africa is not a short-term mitigative option. However, prospects of a longer term disruption would likely spur investment in capacity expansion in alternative market economy country (MEC) supply sources. This report identifies the resources, production costs, and burdens that would be placed on alternative mec producers of chromium, cobalt, gold, manganese, and platinum-group minerals if South Africa's production were subject to a long-term disruption. When long-term supplies from South African deposits are discounted, more than a few years reserves were found only for cobalt and manganese. Even for these two minerals, higher sustained prices would be required to increase manganese production capacity and to support means of cobalt transportation not through South Africa.