Publication details
Y, REE-rich zirconolite from the Skalna Brama pegmatite near Szklarska Poręba (Karkonosze Massif, Lower Silesia, Poland)
| Authors | |
|---|---|
| Year of publication | 2008 |
| Type | Article in Periodical |
| Magazine / Source | Mineralogia Polonica - Special Papers |
| MU Faculty or unit | |
| Citation | |
| Field | Geology and mineralogy |
| Keywords | YREE-rich zirconolite; NYF pegmatite; Skalna Brama; Poland |
| Description | REE-bearing minerals from the Skalna Brama pegmatite were reported by Websky (1865), Traube (1888) and Gajda (1960 a,b). The pegmatite is located within granite of the Karkonosze Massif. It forms lens-like body up to 5 m thick with internal structure comprising from the rim inwards: granitic and graphic zone, blocky K-feldspar and massive quartz core. The rock-forming minerals of the pegmatite include quartz, microcline, oligoclase, biotite. Ilmenite, chlorite, hematite, gadolinite, fergusonite, monazite, zircon, xenotime, uraninite, pyrite and arsenopyrite are accessory minerals. Zirconolite was found as aggregates of needle-like branching crystals up to 4 cm long and up to 0.2 cm wide in massive pink microcline and grey quartz. It shows brown to black color and semi-vitreous to resinous lustre. A sequence of crystallization was determined using BSE images, performed by an ESEM- XL 30 TMP (Philips/FEI) SEM equipped with an EDS (EDAX) detector (Faculty of Earth Sciences, University of Silesia, Sosnowiec). Zirconolite is a first mineral in succession. Fergusonite, monazite, xenotime and zircon crystallized later. EMPA were carried out using a Cameca SX-100 (Masaryk University, Brno). Due to the metamict state, the analysis yield low totals (90-95 wt.% oxides). The composition of studied mineral shows a strong deviation from the stoichiometric composition CaZrTi2O7. The Ca and Zr are very low (0.07 and 0.58 apfu, respectively) and replaced by Y (0.60 apfu), REE (0.32 apfu; HREE>LREE), Sc (0.17 apfu) and U (0.12 apfu). The lowered Ti (1.23 apfu) is compensated by Nb (0.21 apfu), Ta (0.09 apfu) and Fe (0.36 apfu). |