Colour Change of Colourless-Yellowish Scapolite by Electron Irradiation and Heat Treatment

Natural colurless-yellowish scapolite effected by electron beam irradiation and heat treatment were investigated.After electron irradiation, some scapolites turned into purple, and showed a wide absorption band in the green-yellow region.Some other samples turned into more saturated yellow after being irradiated, and the position of the absorption peaks in the UV-Vis absorption spectra were similar with natural scapolite, but with a higher absorbance in purple-blue region.The UV-Vis spectra indicated that the purple colour of irradiated scapolite might have the same genesis as natural purple scapolite, whereas the yellow colour of irraidated scapolite might cause by O^- hole center.The results of heat treatment indicated that heating to 500℃ and holding for 2 hours in reducing atmosphere could not reduce the brown hue of irradiated scapolite, while subjected to 600℃ for 2 hours or 4 hours in reducing atmosphere could make the samples fade.The atmosphere of heat treatment does not produce big difference to the colour change.