CHANGES IN LUMINESCENCE COLOR IMAGES FROM QUARTZ SLICES WITH THERMAL ANNEALING TREATMENTS

Changes in the thermoluminescence (TL) glow curves of quartz grains af ter thermal annealing have been investigated. For the grain samples fr om Madagascar crystal rocks, intrinsic blue-TL (BTL) sensitivity in th e higher glow curve temperature regions is enhanced linearly with the annealing temperature beyond 700 degrees C, while at the same time red -TL (RTL) was newly induced and increased steeply beyond 800 degrees C . Both peaks from BTL and RTL glow curves tend to move towards higher temperatures with annealing temperatures. These results suggest correl ations to beta-quartz/tridymite phase inversion temperature at 870 deg rees C. For Z-cut quartz slices from the Madagascar rock crystal, two- dimensional luminescence images of TL and after glow (AG) have been se mi-quantitatively analyzed using a colour image analyzer with particul ar concern for luminescence property changes accompanied by thermal an nealing treatment at 1000 degrees C. Every luminescence image showed i nteresting stripe or zonal patterns resulting from the crystal formati on conditions. A prominent colour change from the originally weak BTL into RTL and RAG (red-AG) has unexpectedly occurred on the quartz slic es, while the original BTL has transferred into more intense BTL after the annealing treatment. These changes in the TL colour image (TLCI) patterns were also correlated with the aluminium concentrations using images from an electron probe microanalyzer (EPMA). From these results , it was verified that the BTL on the original slice is inversely prop ortional to aluminium and sodium contents whereas both TLCI and AGCI p atterns on the annealed slice offered positive correlation with alumin ium concentrations along the crystal growth direction.