Badanie promieniotwórczości pegmatytów okolic Szklarskiej Poręby metodą klisz jądrowych

Abstract

INVESTIGATION OF RADIOACTIVITY OF PEGMATITES FROM SZKLARSKA PORĘBA REGION BY METHOD OF NUCLEAR PLATES

The measurement of the quantity of radioactive elements contained in the pegmatites from the Szklarska Poręba (Karkonosze) region was accomplished by the method of nuclear plates, exposed to compressed tablets made of the pulverized rock. For four different samples of investigated tablets the author found the following concentrations of thorium and uranium: 1.90 x 10^-5 g/g, 1.34 x 10^-5 g/g, 3.13 x 10^-5 g/g and 5.06 x 10^-5 g/g. She computed the proportion of concentration of thorium to uranium by measurements of long trajectories, and fur the first three samples she obtained a value approximating 1, for sample fourth a value of 0.25. The author identified the radioactive minerals optically in thin sections covered by a liquid nuclear emulsion, and by X-ray analysis of the minerals separated from the samples; the radioactivity of these minerals was determined ,by exposure on nuclear plates.

On the basis of these experiments the author concludes that the mam source of radioactivity of the investigated pegmatites is zircon, fergusonite and monazite and, moreover, that the radioactive substances are concentrated in fractures and at contact surfaces of the mineral grains. The radioactivity of rutile, occurring in one of the samples, the author ascribes to superficial impurities and inclusions.