Arsenic-bearing manganese ore of the Mukulu Enrichment in the Kalahari Manganese Field, South Africa: A new discrimination scheme for Kalahari manganese ore

The Thrusted manganese ore above the Blackridge thrust fault in the Kalahari Manganese Field, South Africa has undergone three significant alterations events, namely the Wessels alteration event, the newly identified Mukulu Enrichment and classic supergene alteration along the Kalahari unconformity. Alteration during the Mukulu Enrichment is manifested in the precipitation of fluorapatite within the thrusted manganese ore, resulting in a distinct supergene-related enrichment in arsenic. Using the low-grade, diagenetic Mamatwan-type manganese ore from Mamatwan mine in the south of the Kalahari Manganese Field as a reference protolith ore, a geochemical distinction has been established between the high vanadium-bearing classic supergene altered ore below the Kalahari unconformity, the arsenic-bearing ore of the Mukulu Enrichment, and the high nickel and copper-bearing, high-grade Wessels-type ore. Utilising these alteration-specific geochemical signatures unique to the area, a new method of ore discrimination has been established for the manganese ore types of the Kalahari Manganese Field.