<p> Nepheline syenite samples were collected from the Bancroft and Blue Mountain areas, Ontario, Canada, and were analysed for K, Rb, and Tl contents by atomic absorption spectrophotometry. The results for these elements and the corresponding K/Rb, K/Tl and Rb/Tl ratios were compared with those of nepheline syenites in various localities, and were found to be similar.</p> <p> The Tl, Rb, K contents and the K/Rb, K/Tl and Rb/Tl ratios in this study were determined to be 825 ppb, 110 ppm, 3.28%, 298, 4.11x10^4 and 135 respectively for the Bancroft nepheline syenite gneisses, and 574ppb, 93ppm, 3.28%, 353, 5.71x10^4 and 162 respectively for the Blue Mountain nepheline syenites. From these data, the nepheline syenite rocks in this study were probably originated as continental plutonics.</p> / Thesis / Bachelor of Science (BSc)