Direct spectrographic determination of major amounts of some rare earths and thorium in allanite

A d.c. arc spectrographic method for direct estimation of Ce, Eu, Gd, La, Th and Y quantitatively and Nd and Sm semi-quantitatively in allanite, a complex rare-earth silicate mineral, is described. Using 3.4 m. Jarrell-Ash grating spectrograph, spectra of synthetic standards and samples mixed with specpure graphite-internal standard mixture in 1:5 ratio, are photographed on Kodak SA-1 emulsion from 2720 A to 3330 A. Pd is used as an internal standard. The determination range of most of the elements cover the range of their natural abundance in allanites. The average standard deviation of the method is +- 15%. The analysis results of one natural allanite sample by the present method are compared with those obtained by XRF method. (author)