Unconventional PGE occurrences and PGE mineralization in the Great Dyke: metallogenic and economic aspects

Platinum group elements (PGE) are strategic materials because 96-99% of the world production is derived from just five mining districts and because th ey cannot be replaced as catalysts in many chemical processes. In order to lessen the strategic character of PGE, both conventional deposits and uncon ventional PGE mineralizations were investigated in an attempt to locate via ble deposits which would diversify the supplier base. In the Great Dyke, co nventional PGE mineralization occurs in the form of pristine sulfide ores m ined underground and oxidic surface ores. New observations such as bimodal distributions of the PGE in the Main Sulfide Zone (MSZ), elevated Pt/Pd rat ios in the oxidized MSZ compared to the sulfidic part and distinct differen ces between the platinum group mineral (PGM) assemblages of the MSZ and str eam sediments of adjacent rivers emphasize the fact that even though the Gr eat Dyke seems to be the second or third largest PGE occurrence in the worl d, the complicated PGE distributions and supergene redistributions should b e kept in mind during planning and mine operation. Investigations of unconv entional PGE occurrences in ophiolites, Alaskan-type intrusions, porphyry c opper deposits and in the Kupferschiefer show that economically e.uploitabl e PGE concentrations can be expected in a broader variety of host rocks tha n considered favourable in the past. In the Albanian Mirdita ophiolite aver age contents of 860 ppb Pt and 60 ppb Pd were detected. Flotation concentra tes of porphyry copper deposits, for example from Mamut, Malaysia, Santo To mas, Philippines, Elacite, Bulgaria, and Ok Tedi, Papua New Guinea, contain between 827 and 1860 ppb Pd + Pt. In selected profiles of the Polish Kupfe rschiefer average contents of 255 ppb Pt, 94 ppb Pd, 2.4 ppm Au and 13.0 pp m Ag were analysed. The distribution of the PGE resources in the world and the annual production rates, however, underline the fact that the chances f or a significant change in the supplier base are relatively low. The Bushve ld Complex will remain the largest producer, followed by Noril'sk-Talnakh, Sudbury and Stillwater. rf the operations in the Great Dyke reach their pla nned capacities, the Great Dyke will rank in third place among the PGE-prod ucing deposits in the world.