The "transition zone" of the deposit is characterized and correlated with the horizon of disintegration and reduction processes of hypergenesis zones. Visual and mineralogical criteria for determining the boundaries of intervals characterized by reduced recoveries from tungsten trioxide ores were tested.

Bauxite deposits of the Turgai Trough, which are one of the raw material bases of the alumina and aluminum industry of the USSR, have been known since 1931. These deposits belong to the platform karst and karst-erosion types. They are associated with locally distributed continental Upper Cretaceous and Lower Paleogene deposits and form three separate groups: the West Turgai, Central, and East Turgai, of which only the first and the third are of industrial significance.