Two contrasting, well preserved Iron Age mines are described from the Nyika Plateau of Malawi. At the first, Ncherenje, about 1600 m³ of material was mined over a linear distance of about 3 km from numerous shallow pits, several large excavations, and a number of underground shafts and horizontal tunnels. Here, low grade ore, ranging from 6.6 to 21.3 wt % Fe₂O₃ with small quantities of iron-enriched ironstone averaging about 35%, was excavated from the regolith which had developed upon gneissic bedrock. The second mine, at Mbiri, is a single excavation where about 15.5 m³ of magnetite-rich, partially weathered gneiss averaging 58% Fe₂O₃ was mined. Ethnographic studies as well as evidence from the mines themselves indicate that the low grade ore from Ncherenje was preferred by the smelters. The Mbiri ore contains insufficient silica to make a fayalite slag, a problem which can be overcome by adding old slag and lower grade material to the charge. Their two-stage smelting technology, however, employs a primary natural draft furnace which essentially cannot produce high enough temperatures to melt high grade magnetite; it was apparently designed to process only low grade ore.