| Popis: |
Three groups of fluorapatite from the Mont Saint-Hilaire igneous complex in Quebec, Canada have been analyzed with scanning electron microscopy (SEM), electron probe microanalyses (EPMA), single-crystal X-ray diffraction (SCXRD), Fourier transform infrared spectroscopy (FTIR), and magic angle spinning nuclear magnetic resonance (MAS-NMR) to fully characterize the chemical and structural details of fluorapatite from one of the most mineralogically diverse locales on Earth. SEM and EPMA revealed these fluorapatites to be enriched in Th, Y, and Na, while FTIR showed substantial concentrations of carbonate substituting for phosphate at the tetrahedral site. The Th contents observed in these fluorapatites are the highest ever observed for natural samples, and have implications for designing new solid nuclear waste forms. SCXRD refinements revealed the dissymetrization of two of the three groups from the classic P63/m space group to the P-3 space group due to the elevated Y and Na contents. Lastly, the FTIR and NMR data show the presence of the long debated C-F bond the observation of which has important implications for the incorporation of carbonate groups into apatites, and is the first time this bond has been observed in any natural mineral. |
