A study on mineralogical characteristics of huanghoite-(Ce)in the Bayan Obo deposit
The Ba-REE fluorocarbonate minerals,belong to a unique class of rare earth minerals in the Bayan Obo deposit.They have been studied regarding on the basic crystal chemistry by large numbers of previous researches,while they have been relative limitedly studied regarding on their paragenetic mineral assemblages,chemical compositions and other aspects.Some coarse-grained crystals of huanghoite-(Ce)found in the orebody have been studied in this paper by using the field emission scanning electron microscope,field emission electron microprobe and other analytical instruments.The results show that the Huanghoite-(Ce),occurred mostly in forms of veins and agglomerated aggregates in the ore,are closely intergrown with barite,fluorite and fluorocarbonate minerals,with typical distribution characteristics of hydrothermal minerals.Electron microprobe analyses show that the chemical composition of huanghoite-(Ce)is mainly composed of BaO(35.28%)and light rare earth elements(39.37%).In addition,due to the isomorphous replacement of elements,there is the intercrescence structure of huanghoite-(Ce)-bariocebaite-(Ce)-parisite and other minerals locally.Combined with the previous chronological evidence and the present mineral paragenetic assemblage relationship of huanghoite-(Ce),it is believed that the huanghoite-(Ce)in the Bayan Obo deposit mainly crystallized and precipitated in the F-,Ba-and REE-rich hydrothermal fluids in the Paleozoic era,whereas its REE elements were mainly originated from the remobilization of the rare earth minerals formed in the early period.
Bayan Obo deposithuanghoite-(Ce)chemical compositionscanning electron microscopeelectron microprobe