Britolit-(Y): neskoromagmatický akcesorický minerál Y-REE z granitu A-typu v Stupnom pri Považskej Bystrici, Pieninské bradlové pásmo (severozápadné Slovensko)

Pages 224-229
Bulletin mineralogicko-petrologického oddělení Národního muzea v Praze | 2008/16/2

Britholite-(Y): a late-magmatic, Y-REE-bearing accessory mineral from A-type granite in Stupné near Považská Bystrica, Pieniny Klippen Belt, north-western Slovakia Accessory britholite-(Y), (Y,REE,Ca,Th)5(SiO4,PO4)3(F,OH,O), forms 30 μm large inclusion in quartz from Permian A-type granite pebble in Cretaceous flysch sequence of the Pieniny Klippen Belt, Western Carpathians, Slovakia. Britholite shows compositional zoning with variable REE/Ca ratio (6 to 26 mol. % of apatite end-member) and 0.40 - 0.47 apfu F. (Y,REE)SiCa-1P-1 is the main substitution mechanism in the mineral. It contains 2.6 - 4.7 wt. % ThO2 (0.07 - 0.13 apfu Th), the highest Th contents yet reported in naturally occurring britholite-(Y). Textural and compositional data indicate their origin by alteration and partial replacement or overgrowth of primary apatite in late-magmatic, fluid-rich conditions.

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