A GEOCHEMICAL AND MINERALOGICAL INVESTIGATION OF THE ORDOVICIAN EUREKA QUARTZITE FOR USE AS A SILICON ORE FOR PHOTOVOLTAIC CELLS SHOWS PROMISE FOR PLASMA FURNACE PRODUCTION

The production of silicon for photovoltaic cells is an energy intensive process that is sensitive to impurities. Silicon for solar cell applications is required to be 99.999% pure or “5 nines” whereas high grade electronics requires 99.9999999 or “9 nines”. Thus finding silica ore (quartz-rich ore) that is already low in impurities or that has impurities of significant value to offset costs is highly desired and is an economic requirement for advancing this renewable energy technology. A sample set of unknowns from the Ordovician Eureka quartzite in eastern Idaho was investigated to assess purity and to determine the nature of waste if processed by plasma furnace. A comparison was made with older existing private data. The mineralogy and geochemistry of unknown samples is very consistent with previous reports with unknown quartzite samples having silica contents between 96.475 and 99.659 weight percent. The values are approximately 0.9 weight percent higher than previous analyses and this may be a local sampling effect or inter-lab instrumentation differences. The mineralogy is dominated by quartz as determined by powder diffraction and scanning electron microscopy. No minerals or materials of environmental concern were identified that would negatively impact processing, such as lead, arsenic or mercury minerals. Primary impurities are potassium feldspar, illite-sericite and iron oxides. Gold was detected in trace amounts in 40% of the analyses and at concentrations that are approximately an order of magnitude lower than the previous reports. No other unexpected economic resource mineral or material was identified. Waste generated from a plasma furnace operation would produce approximately 0.48 oz. of gold per metric ton on average. Further exploration of the area to identify higher gold concentrations within the Eureka Quartzite locally may be justified.