The nature of spheroidal gold of the Middle Kyvvozh placer in the Middle Timan

A comprehensive mineralogical study of 13 samples of spheroidal gold from schlich concentrates of the Middle Kyvvozh gold placer, which is part of the Kyvvozh gold placer field located in the central part of the Volsk-Vym ridge of the Middle Timan, was carried out. The presence of both natural and technogenic gold in concentrates was established. Natural placer spheroidal gold is characterized by a worn surface with oxide films and the development of a high-grade corrosion rim. Technogenic gold spheroids have a polygonal-mosaic tuberculate-pitted or smooth surface, the presence of aluminosilicate glasses and slags in the form of crusts or inclusions in the matrix, the presence of mineral inclusions and impurities of platinum group metals, tin and lead, which are not characteristic of native gold. Natural spheroids were formed by natural smoothing in the water flow during the formation of the placer. The formation of technogenic spheroids is associated with the impact of high-temperature plasma on the concentrate enriched in placer gold and platinoids, which occurs during electric welding undertaken during the repair work of the flushing devices. The results of the study should help to avoid errors in the interpretation of the genesis of such gold and, as a result, in determining the nature of the primary sources of placers.