The chemical and mineralogical composition of the clay slate of the Dzherdanak deposit is determined. Four species were investigated in the natural and heat-treated state in the range of 800-1400 °C using the X-ray method. Established phase changes undergoing breed. The phase composition of the original rock, intermediate substances during roasting up to 1400 oC has been determined. The initial phases in all varieties are quartz and mica of different composition. One variety contains kaolinite. The main phases formed during high-temperature processing are mullite, quartz and cristobalite. The structure of natural and heat-treated samples was studied by scanning electron microscopy. The sizes of mullite crystals are in the range of 3.5 to 0.15 μm, depending on the type of rock. For the three varieties of shale C-1, C-2, and C-3, amorphous regions are separated, separated by a lighter bounded phas
