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Luminescence Spectra of Alkali Feldspars: Influence of Crushing on the Ultraviolet Emission Band

Abstract Grinding and milling processes lower the intensity of the ultraviolet emission band of alkali feldspars. The luminescence spectra of aliquots of natural transparent adularia from Saint Gothard, Switzerland, that were crushed at different energies, show the irreversible collapse of the UV 290 nm peak. Simultaneously, the 390 nm blue emission increases in accordance with the milling treatment, which reduces the presence of ionic charge compensators (Na+) and sensitizes the structure (producing [AlO4]° centers). The annihilation of the 290 nm UV peak by crushing could be linked with cracks-strain-exsolution features of the lattice of adularia. For this reason, the use of this 290 nm peak and energetic milling treatments in dating and dosimetric routines, should be rejected.