Causes of Geophagy by Ungulate Animals in the Caucasus Mountains

This article is aimed at identifying the cause of rock eating by wild herbivores in the territory of the Caucasian State Biosphere Reserve in the Caucasus Mountains. The research focused on the mineralogical and geochemical features of the rocks eaten and the geological conditions of their formation. This report includes a comparative analysis of the mineral and chemical compositions of the consumed rocks and of animal faeces consisting almost entirely of mineral matter. It was found that the rocks consisted mainly of hydrous and chlorite and that they derived from Proterozoic schists altered in the zone of tectonic contact. The near complete absence of sodium consumed in the rocks as well as the selective removal of heavy rare earth elements from the body by mineral sorbents suggest that the geophagy by animals in the Caucasus is associated with features of the metabolism of lanthanide elements.