ON RELATIONSHIPS BETWEEN THE CONTENT OF NIOBIUM, TANTALUM, THORIUM, AND URANIUM IN RARE-METAL CARBONATITES

A quantitative relationship between concentrations of niobium, tantalum, uranium, and thorium in a rare-metal carbonatite deposit is sustained, in its main features, in some others of the same type, as well as in pyrochlore fractions from a larger number of sources. The tantalum-niobium and uranium-thorium ratios are higher in the terminal products of magmatic activity than they are in its earlier products. The interrelations of the concentrations of the four elements, as ratios, are so relatively consistent that, knowing the concentration of any two of the four, it is possible to estimate the concentrations of the other two. V. P. Sokoloff