LUMINOGEN GENERATION IN RARE-METAL PEGMAT ITE K-FELDSPAR AS AFFECTED BY GEOCHEMICAL AND CRYSTAL-CHEMICAL FACTORS

X-ray luminescence spectra of K-feldspars from various rare-metal pegm atites were studied. Differences observed in luminescence characterist ics reflect differences in temperature, acidity-alkalinity, alkali acc umulation in polymetal and Li-pegmatites, and the structural state of K-feldspar. The variability of X-ray luminescence characteristics acro ss large monocrystals is caused by fluctuations in crystal growth rate and nonuniformity of structure ordering and impurity distribution. Ra re-metal mineralization is detected by enhanced luminescence in the UV and IR spectral ranges, reduced AlO44-/Tl+ ratio or Tl+ abundance. Th e Mn2+/Tl+ ratio is proposed to determine the relative acidity-alkalin ity in rare-metal pegmatites.