Zircon in fluvial deposits of the upper course of the river Luznice and its relation to anomalies found by aerial monitoring

The mineral zircon and the uranium and thorium contents were examined at sites of gravel sand extraction. The concentrations depend on sand grain size, the U and Th contents being about twice as high in fine fluvial sands than in coarse sands. The higher radioactivity of fluvial deposits was observed by aerial monitoring and confirmed by ground measurements. Zircon is a radioactivity carrier in heavy mineral concentrates, together with monazite. The zircon content of sediments is about 50 to 75 g/m3. Given a large volume of material extracted and its perfect use, heavy minerals may be extracted as by-products during the extraction of gravel sand. (M.D.). 1 tab., 3 figs