Iron formations occur within the metasedimentary/metavolcanic sequence of the Chuos Formation in the Southern Margin Zone of the upper Proterozoic Damara Orogen of South West Africa/Namibia. The iron-rich lithosome comprises magnetite-quartz rock, haematite-quartz rock and magnetite-quartz-silicate - carbonate rock. On the basis of their host rock associations, iron formation in diamictite sequences and in amphibolite are distinguished. Iron formation in amphibolite is developed both as a chemical sediment and as a composite rock consisting of chemical iron-rich sediment with admixture of varying amounts of volcanic detritus. Iron formation in diamictite represents a pure chemical sediment. Both of the iron-rich rocks contain abundant apatite and their manganese contents are low. An exhalative origin for the iron formations of the Southern Margin Zone related to mafic volcanism and ensialic rifting is suggested.