Влодавец, В. И. Нефелино-апатитовые месторождения в Хибинских

40—70% of nepheline and 5— 1 0 % of aegirine-augite, biotite, sphene and ore mineral. Thanks to such distribution of minerals the denomination of these genetically closely related rocks presents great difficulties. According to the principle of rational petrological terminology of denominating the rocks after their first syllable :), the writer named the former rock, rich in apatite, a p a n e i t e , and the second, poor in apatite and rich in nepheline—n e a p i t e. The results of field analyses are shown in Tables 5 and 6 for the Kookisvumchorr-deposit. In Table 8 is shown the estimated amount of useful components of the nepheline-apatite deposits. Table 9 gives the results of an attempt to determine by optical method the percentage of P 2 0 5 in mean samples of nepheline-apatite rocks. The last two chapters contain some considerations as to the use of nepheline-apatite rocks, as well as to conditions of transport and of exploitation of the deposits. J) D. В e 1i a n к i n. On the Term ,.Rock-: and on Petrograplilcal Classification and omenclatnre. Travaux du Mnsdc Miner, pres l’Ac. des S ', de I'URSS. Т. III. 1929.