The book is devoted to the study of hydrothermal conversion leading to the formation of zeolites of complex aluminosilicates – halloysite, kaolinite, anthigorite, dolomite and obsidian by X-ray diffraction, thermogravimetric and X-ray spectral analysis. Zeolites are a perspective type of non-metallic minerals. With their high adsorption, ion exchange and catalytic properties they are increasingly used in various branches of science, industry, agriculture, ecology etc. The book also gives information about zeolites synthesized for the first time in the above systems and proves their zeolitic character. The book is intended for a wide range of experts in the field of inorganic and structural chemistry, chemical engineering, crystal chemistry, mineralogy.