Publication details
Re-investigation of 'minasgeraisite-(Y)' from the Jaguaracu pegmatite, Brazil and high-temperature crystal chemistry of gadolinite-supergroup minerals
| Authors | |
|---|---|
| Year of publication | 2023 |
| Type | Article in Periodical |
| Magazine / Source | Mineralogical Magazine |
| MU Faculty or unit | |
| Citation | |
| Web | https://doi.org/10.1180/mgm.2023.19 |
| Doi | http://dx.doi.org/10.1180/mgm.2023.19 |
| Keywords | gadolinite; beryllosilicate; minasgeraisite-(Y); Raman; Jaguaracu Pegmatite; single-crystal X-ray diffraction; high temperature |
| Description | The chemical composition (including B, Be and Li), the Raman spectrum and the crystal-structure evolution (at the temperature range 27-1000 degrees C) of a Mn-bearing, Bi-rich gadolinite-subgroup mineral from the Jaguaracu Pegmatite, Brazil (type-locality of minasgeraisite-(Y)) was studied. Elemental mapping revealed that the crystal investigated has complex chemical zonation with various Bi (similar to 8-24 wt.% Bi2O3), Ca (similar to 8-10 wt.% CaO) and Y (similar to 11-17 wt.% Y2O3) content. The sample investigated has all the specific features of the chemical composition of minasgeraisite-(Y), except Ca excess and, thus, should be considered as hingganite-(Y). The Raman spectrum of the sample under study has bands at 140, 179, 243, 350, 446, 519, 559, 625, 902, 973, 3224, 3353, 3532 and 3763 cm(-1), and is similar to that of hingganite-(Y) /-(Nd). Crystal-structure refinement confirmed that the crystal in question should be considered as hingganite-(Y) and is in line with the previously obtained data on gadolinite-subgroup minerals from the Jaguaracu Pegmatite. High-temperature single-crystal X-ray diffraction studies revealed that the mineral starts to decompose above 800 degrees C. We can conclude that beryllosilicates are most stable at high-temperature conditions within the gadolinite supergroup and that species with a higher M-site occupancy have higher stability upon heating. |