Detection of irradiated foods by luminescence of contaminating minerals - effect of mineral composition on luminescence intensity

Laboratory irradiated rock and mineral samples were studied for their lumin escence properties. The effect of alteration of feldspars on luminescence i ntensity was determined by the autoradiographic method for porphyritic gran odiorite planar rock samples and with the TL reader for crushed minerals. F eldspars and quartz exhibited more intensive luminescence than mafic minera ls, and luminescence of fresh K feldspar was the most intense. Potassium co ncentration did not have any effect on luminescence intensity for K feldspa rs but the intensity was highly dependent on the alteration degree of the m ineral. Decrease in luminescence was found without a change in the element composition of the mineral and alteration was due to sericitization of K fe ldspar. (C) 1999 Elsevier Science Ltd. All rights reserved.