Three types of secondary pretulite (ScPO4) from Dolní Borypegmatites, Czech Republic - evidence for high Sc mobility inhydrothermal environment.

Three types of secondary pretulite (A, B and C) were identified from pegmatites in Dolni Bory, Czech Republic. All pretulite types formed by recrystallization of two different Sc-enriched precursor minerals: Sc,Y,U,P-rich zircon and complex W-Nb-Fe-Sc oxide. Formation of pretulite took place at approximately 350°C and 2 kbars. Pretulite A occurs as inclusions together with prevailing inclusions of xenotime-(Y) in recrystallized zircon. Pretulite B originated by recrystallization of the W-Nb-Fe-Sc oxide and its composition spans over almost whole ScPO4-ZrSiO4 solid solution. Pretulite C has been found away from the precursor minerals in association with pyrophyllite replacing andalusite. Composition of the fluids, which were poor in fluorine, allowed selective mobilization of Sc and its separation from HFSE.