ON THE CORRELATIVE BONDS OF THE RARE-EARTH ELEMENTS AND SOME PECULIARITIES OF RARE-EARTH SEPARATION IN THE PROCESSES OF ENDOGENOUS MINERAL FORMATION

The study of variations in the composition of rare earths in a number of minerals of a different genesis (monazite, rinkolite, sphen, apatite, perowskite) with the aid of a correlative "lanthanum" graph shows that in many geochemical processes a division of the rare earths into two groups, "more basic" and "less basic" elements, is observed. Being determined by concrete geochemical conditions, the composition of the indicated groups is not constant. Only in some cases (approximately equal activity of ceric and yttric earths) these groups correspond to ceric and yttric earths. The change in the composition of both groups occurs conjugated which is displayed in the constantly observed multiple correlationdirect and inverse-of all the rare earth elements. The composition of the group of rare earth elements which isolate from the solution determines the possibility of the appearance of selective or complex compositions of the rare earths in the minerals of the same paragenesis. (auth)