Chiang Mai Journal of Science

 Effect of gamma rays on changes color of rubellite tourmaline from Afghanistan, Mozambique and Nigeria were studied. The gamma irradiation process was done using cobalt-60 radiation; the samples were irradiated to 100 Mrad. Most samples had their color changed. It was obviously seen in the Afghanistan samples. Their optical spectra were investigated by UVVis spectroscopy. After irradiation, most samples showed stronger absorption band of Mn³⁺, centered at 520 nm. Additionally, the irradiated Mozambique and Nigeria samples became darker brown tint related with an increasing of Fe²⁺-Ti⁴⁺ IVCT absorption band. The trace elements analysis proved that the Afghanistan samples contained higher manganese than the samples from Mozambique and Nigeria. In the other hand, the iron content of Afghanistan samples were much lower than that of Mozambique and Nigeria samples.