Abstract:
The monazite group minerals (LREE, Ca, Th)[PO4] are the most important LREE-carriers in the rocks of the Earth. Monazite-(Ce) is considered the most abundant REE-bearing mineral. The monazite group includes anhydrous monoclinic phosphates, arsenates, and silicates of LREE, Ca, and Th: monazite-(La), monazite-(Ce), monazite-(Nd), and monazite-(Sm) LREE[PO4], cheralite-(Ce) (Ce, Ca, Th)[PO4], gasparite-(Ce) Ce[AsO4], brabantite CaTh[PO4]2, and huttonite Th[SiO4]. Cheralite-(Ce) is the intermediate member in the brabantite–monazite-(Ce) series. The abundance of monazites sharply decreases from monazite-(Ce) to monazite-(Nd), monazite-(La), and monazite-(Sm).
