ЦЕРИЕВЫЙ БРИТОЛИТ МУШУГАЙСКОГО МЕСТОРОЖДЕНИЯ (МОНГОЛИЯ)

Abstract

In Mushugai deposit, britolite was found in pyroxene-calcite rocks occurring among syenites. By the data of electron microprobe analysis and scanning electron microscopy (LEO-1430) with energy-dispersion spectrome-ter IncaEncrgy-300, this britolite is characterized by heterogeneous distribution of the major components and the presence of higher amounts of fluorine (up to 0.8-0.9 f. a). The heterogeneity of its composition shows two ty- 90 pes: mosaic and rhythmically zonal ones. The mineral contains higher quantities of CaO and P2O5 but the lower contents of SiC>2 and REE. There arc inclusions of monazite and other rare-earth minerals in its grains, in some cases they are characterized by the La dominating among REE. One group of them correspond to phosphates with La/Се ratio varying from 2 : 1 up to 4 : 1; another group - carbonates with La/Cc ratio from 4 : 1 to 6 : 1. The Mushugai ore deposit contains mineralization of apatite with the REE contents as high as 12-16wt% TR2O3, there is up to 25 % of britolite minal in this mineral. Electron scanning has shown heterogeneous compo-sition of apatite. For example, the REE contents vary from 3-4 to 7-8 wt% within an apatite grain, in correla-tion with the silica amount which may rise up to 6--8 wt%. Analysis of results, together with data on compo-sitions of britolite and apatite from other deposits and regions, allow to assume existence of the continuous iso-morphous series formed by these two minerals.