PYROCHLORE IN ONGONITES FROM VERKHNEURMIYSKY MASSIF (RUSSIAN FAR EAST)
Pyrochlore group of ongonites in Verkhneurmiysky granite massif (Badzhal-sky area, Russian Far East) are described. Composition and formations order of pyrochlore are characterized. For the first time in the Far East two rare species of pyrochlore (as prevalence of formation) are established: bismutopyrochlore, uranpy-rochlore. All two species are formed by metasomatic replacement of earlier accessory minerals: niobian wolframite, samarskite, ishikawaite, wolframoixiolite, scheelite, fergusonite. Far East pyrochlore it is characterised by extremely high concentration of tantalum and tungsten in a skeleton of a crystal lattice B and of uranium, bismuth, iron in a position A.