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The Red Syenite deposit on the farm Zanddvierspoort 210 JF, locatud on the pedphery of the Pilanesberg Alkaline Complex, is eonsidered here as a potential source of nepheline syenite, a material that is used as a flux in the maliufacturing of glass and ceramics. Glass and ceramics manufacturers have different specifications as far as the quality and the product for¡n is concerned. Local glass manufacturers generally require heneficiated material with a low Fe content, depending on the kind of glass being manufactured. Ceramics manuf;ictures also require material with a low Fe content, but the material may be unbeneficiated as most of these factories already have facilities to remove Fe and other materials considered deleterious to the product or manufacturing process. The minimum requirement is that the material must be caished and milled to a specific size fraction (< 10 mm). A common concern expres.setl by the industry' is the requirement tor continuity of production, and an assurance of consistent quality from the supplying deposit. The availability of feldspar as an alternative starting material, al a lower cost than nepheline syenite, is responsible for an unwillingness of potential users to switch to nepheline syenite, despite its proven advantages.Extensive additional geological confirmation is required to estimate the sized and quality of the resource of the nepheline syenite in the Pilanesberg Alkaline Complex. To demoastrate its viability, a preliminary investigation has been undertaken on one such a deposit to show that the deposit will probably be able to .sustain production over a considerable period and display internal homogeneity that would ensure the consistent qLialíty of the material produced. Given the uncertainties in all paranieter considered at this stage it must be .stressed that the financial .study is merely used to highlight the projects potential viability and to identify its risks. For this purpose a hypothetical project was designed which shows that such an operation would be most sensitive to the production rate, capital rec|uired, and the selling price of the product. Transport and operating costs show a less significant influence on the viability of the project.

The Prieska orebody is contained in high-grade metamorphic peraluminous rocks. Birdwingshaped rare earth element profiles and high ½Na values are observed in rocks under the ore. These characteristics are interpreted to reflect an early magmatic-dominated alteration stage during which heavy rare earth elements and highly radiogenic Nd were added to the rocks. Rocks studied above the ore display normal rare earth element profiles and country-rock The generally high Mg/Fe ratios of all the altered rocks are thought to indicate pervasive late alteration by seawater-derived fluids. The alteration processes appear to be linked to the cooling of a hypothetical high-level intrusion derived from the depleted mantle. The existence of this type of magmatism is also indicated by the occurrence of amphibolites higher up in the sequence which have fiat rare earth element profiles and high fNd. Introduction THE Prieska mine at Copperton in the northern CapeProvince of South Africa (Fig. 1) exploits a massive sulfide deposit (60 million tons of Cu-Zn ore) of Proterozoic age.The present study concerns the metamorphic peraluminous rocks which form an envelope around the orebody. The geochemical evidence for their origin is examined, emphasizing the unusually shaped (birdwing) rare earth element graph profiles that resuit. The peraluminous rocks were described and interpreted as metamorphosed alteration products by Middleton (1976) and Theart (1985) whereas Wagener (1980) and Wagenet and Van Schalkwyk (1986) regarded them as metamorphosed chemical sediments. Geology of the Prieska Deposit The Prieska deposit is the biggest of several massive sulfide deposits in the Areachap Group of the eastern Namaqua province. The rocks around the mine have been defined as the Copperton Formation comprising the Smouspan, the Prieska Copper Mines, and the Vogelstruisbult Members (Cornell, 1978; Cornell et al., 1986). Peraluminous rocks accompanying the ore form the major part of the Prieska Copper Mines Member which also contains the massive sulfide body, lenses of carbonate and anhydrite rocks, and thin layers of banded Mn silicate. The peraluminous rocks contain minor amounts of sulfides and their mineral assemblage varies from quartz-perthite-sillimanitecordierite-phlogopite (here termed sillimanite-cordierite rock) to gedrite-anthophyllite/cummingtonite-* Present address: South Africa. (Fig. 2). The Smouspan Gneiss is interpreted as a metadacite (Theart, 1985). The Vogelstruisbult Member contains peraluminous gneisses and amphibolites which have been interpreted as metapelites and metabasalts, respectively. phlogopite-tourmaline (gedrite rock), the former being predominant. The steeply dipping Prieska Copper Mines Member is bounded to the southwest by the Smouspan and to the northeast by the Vogelstruisbult Members SamplingAll samples are from diamond drill cores. The sample number prefix is the number of the borehole. Borehole V38 was drilled from the surface, all other boreholes were drilled from underground and start in the Smouspan Member...