MERITS OF USING BARIUM AS A HEAVY ABSORBER IN MAJOR-ELEMENT ANALYSIS OF ROCK SAMPLES BY X-RAY-FLUORESCENCE - NEW DATA ON ASK-1 AND ASK-2 REFERENCE SAMPLES

It has been demonstrated that XRF analysis of fused discs doped with B a instead of La can give acceptable results for major element analysis of silicate rock samples, which are comparable to those obtained from La-doped fused discs. Replicate analysis of reference samples using B a-doped fused discs indicated an analytical precision of approximately 1% and an accuracy of better than 3% for most of the elements, Anothe r advantage of using Ba as a heavy absorber was that it allows simulta neous determination of Na along with other major elements on the same disc. Sodium levels determined by this method are in good agreement wi th the results of XRF analysis using pressed powder pellets, However, with Ba-doped discs there could be some difficulty in the determinatio n of Ti and Mn as Ba L alpha 1 and L tau 2 lines are in close proximit y to Ti and Mn K alpha lines, respectively, causing enhancement of the background signals of Ti and Mn. This can be avoided by carefully sel ecting suitable background angles, New major elemental analytical data are provided for the Norwegian reference samples ASK-1 (larvikite) an d ASK-2 (schist) as the recommended values for these are not available in the literature.