Kudurs (mineral licks) in the Belukha Mountain area, Altai Mountains, Russia.

Studies were carried out in the upper reaches of the Akkem River aimed at explaining why the local ungulates consume clay rocks common in the basin of the Yarlu River, a tributary of the Akkem River. Chemical composition of river and spring waters and mineral and chemical composition of clay rocks consumed by wild and domestic ungulates at kudurs were studied. The waters in the local watercourses are ultra-fresh, hydro-carbonate-calcium. Increased concentrations of rare-earth elements (REE) were observed in waters of the Yarlu River. Consumed clayey rocks (kudurits) are represented by finely dispersed quartz-plagioclase-mica-chlorite mineral associations — the products of transformation of shale rocks of the Early Paleozoic age. The comparison of the chemical composition of kudurits and coprolites of red deer showed that when the rocks pass through the digestive tract, out of all macroelements, only Na is reliably assimilated in the body in amounts from 0.1 to 0.3 g per kg of kudurit. In addition, kudurits act as sorbents, removing P, K, Mg, and sometimes Ca from the body. As part of micronutrients, they are most active in sorbing and removing REE from the body. [ABSTRACT FROM AUTHOR]