Rare-metal zircon rims in lithium-fluorine granites of the Far East

Abstract

766 Zircon of rare metal lithium–fluorine granites is characterized by a high concentration of isomorphic admixtures and rare element microminerals [1]. We observed two types of zircon grains in lithium–fluo rine granites of the Far East: (1) with the core relatively depleted in admixtures and rare metal rims; (2) with out a core, with a maximal concentration and spotty zoned distribution of rare elements [2]. The first type was formed during crystallization of a melt containing zircon crystals captured during palingenesis. Transfor mation of protocrystals was accompanied by over growth of rims enriched in minor elements and min eral inclusions (xenotime, uraninite, thorite, mona zite, and others). Investigation of the composition of rare metal zircon rims has clarified the history of crys tallization of the lithium–fluorine granite melt.