Temperature-versus compositional-induced structural deformations of gadolinite group minerals with various Be/B ratio

Abstract Gadolinite crystals from Mogov (Tajikistan), Dorozhniy (Tajikistan), Dara-Pioz (Tajikistan) and Osterby (Sweden) with different Be/B ratio (0.56–191) were studied by single crystal X-ray diffraction, energy dispersive and wavelength-dispersive X-ray analysis and inductively coupled plasma–optical emission spectrometry to compare their crystal chemistry features. Besides, Raman spectra and thermal behavior at low (from −173 to +67 ​°C) and high (from +25 to +1100 ​°C) temperatures of gadolinite-(Y) from Osterby (Sweden) was investigated in order to study recrystallization and obtain the thermal expansion coefficients. It was shown that thermal expansion of gadolinite-(Y) (Y2Fe2+Be2Si2O10) is very close to the expansion of datolite (Ca2B2Si2O8(OH)2). Comparison of the temperature and chemical deformations confirms the main rules of comparative crystal chemistry.