REE Minerals in the Rocks of the Katugin Rare Metal Deposit, East Transbaikalia: Behavior of Lanthanides and Y during Crystallization of an F-Saturated Agpaitic Melt

The chemical composition and origin of major REE minerals of aegirine, aegirine–arfvedsonite, arfvedsonite, and annite–riebeckite–arfvedsonite granites are studied for the Katugin Ta–Nb–Zr–Y deposit with cryolite in the southwestern part of the Aldan Shield. The REE mineralization of granites includes two types: (i) disseminated grains of pyrochlore and, to a lesser extent, other Nb– Ln oxides, Ln phosphates, and Ln –F carbonates in association with zircon, ilmenite, sphalerite, and other minerals and (ii) interstitial intergrowths of Ln fluorides.