DETERMINATION OF COLUMBIUM IN ORES BY X-RAY FLUORESCENCE1 JouN S. SrevrNsoN, McGill Uniaersity, Montreal, Quebec. AssrRecr

Analyses for columbium in pyrochlore ores from North Bay, Ontario, have been made successfully by using o-ray fluorescence techniques. rt was necessary to use, as in methods of optical spectroscopy) an internal standard for this work. The choice of a suitable internal standard for a particular metal in a specific mineral association or ore-t).pe requires consideration of the characteristic r-ray spectrum and absorption edges not only of the metal to be analysed for but also of the metals with which it is associated. For these reasons, molybdenum was found to be a suitable internal standard for columbium in the analyses of these ores.