U-, Th- and REE-bearing accessory minerals in a high heat production leucogranite within the Galway Granite, western Ireland

A microprobe analysis of the accessory minerals in the Costelloe Murvey granite demonstrated the following results. All analysed minerals contain U and Th. The light REE are strongly partitioned into monazite and into both the Ce-bearing silica-rich and silica-poor phases. The heavy REE are hosted principally by thorite, zircon and the U-Th-Ti-Nb-bearing phases. (4) The low-total thorites have high levels of light REE relative to the high-total thorites. The uraninite contains high levels of middle REE. The zircons have variable totals and are Y-rich. One grain displays an inverse relationship between Y and Zr. In this grain the Y-rich spot displays higher levels of heavy REE than the Y-poor spot.