The chemical composition (including B, Be, Li), the Raman spectrum and the crystal structure evolution (at the temperature range 27–1000 °C) of Mn-bearing, Bi-rich gadolinite subgroup mineral from the Jaguaraçu Pegmatite, Brazil (type-locality of minasgeraisite-(Y)) was studied. Elemental mapping revealed that the crystal being investigated has complex chemical zonation with various Bi (~8-24 wt.% Bi2O3), Ca (~8-10 wt.% CaO) and Y (~11-17 wt.% Y2O3) content. The sample in hand has all 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 consists of the number of bands (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 Jaguaraçu Pegmatite. High-temperature single crystal X-ray diffraction studies revealed that the mineral starts to decompose above 800 °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.