Tripartite division of the system 2REEPO4-CaTh(PO4)2-2ThSiO4, discreditation of brabantite, and recognition of cheralite as the name for members dominated by CaTh(PO4)2

The nomenclature for the system 2REEPO(4) - CaTh(PO4)(2) - 2ThSiO(4) has been revised, to be consistent with CNMMN principles. Henceforth. only three names will be applied to members dominated by the respective end-member compositions monazite, cheralite, and huttonite. The name cheralite has priority over brabantite, which hereby is discredited. A six-fold diagram is replaced by a three-fold nomenclature diagram to conform to IMA rules. The parameters of cheralite are redefined. This proposal, IMA 2005/F was approved by the CNMMN in April 2006.