Abstract
The increasing demand for critical metals, such as the rare earth elements (REE), and the desire to become less dependent on Chinese resources has spurred global interest in search of economically viable REE deposits in other countries. Although the main economic interest in the Rustenburg Layered Suite (RLS) has been focused on the well-known Platinum Group Elements (PGE), Cr, and the world’s largest resources of V, Ti, and Fe, the Upper Zone (UZ) also contains vanadiferous titano-magnetite and apatite-ilmenitemagnetite mineralization at its bottom and top sections, respectively. Using regional soil geochemical data, Council for Geoscience delineated some of the known mineral deposits of the RLS in addition to new potential exploration targets, particularly for apatite ± REE in the Roossenekal area. The apatite ± REE potential areas were based on the TiO2 – Y – Fe2O3 (t) as proxies due to the limited regional soil data. In this study, one of the apatite potential areas, located southwest of Roossenekal, was selected for a followup investigation to verify the regionally outlined apatite target area and assess the reliability, effectiveness, and limitations of regional soil data in apatite exploration as well as assess the economic potential of the area. This was achieved by a detailed high-density soil sampling as well as grab rock sampling. The results reveal that Y correlates well to apatite, but not REE. Petrographic studies of olivine diorites show appreciable amounts of apatite, occurring both as inclusions and as an interstitial phase. In places, Y anomalies spatially coincide well with P2O5 anomalies in soil data and they occur over areas mapped as olivine diorites. The results demonstrate that the regional target areas based on TiO2 – Y – Fe2O3 (t) proxies, are representative of apatite mineralization and the high-density soil sampling is useful for followup work on regional soil geochemical targets. Although there may be significant apatite in the rocks, apatites are rather low in REE content and as such, the preliminary assessment of economic viability for apatite ± REE in the current study appears to be too low as compared to the world-renowned Phalaborwa deposit. Consequently, the apatites from the Bushveld are not a good target for REE enrichment, and their economic viability is greatly insignificant.
M.Sc. (Geology)