Data are presented on the results of X-Ray structural and thermal analyses, data from chemical and microscopic studies of serpentines of chrysotile Mg3Si2O5(OH)4 – pecoraite Ni3Si2O5(OH)4 series from the silicate nickel deposits in the Urals. Nomenclature is updated of the studied serpentines following the regulations of the International Mineralogic Association. It is demonstrated that the studied minerals are the chief ore minerals in serpentinite zones of nickel fields. Issues are reviewed of formation of serpentines of the chrysotile-pecoraite series in conjunction with hydrothermal processes. It is suggested the two-tier structure of the Ural supergene nickel fields, where supergene upper tier has "roots" in the form of hydrothermal lower tier, which significantly expands the area of the search for new fields and opens great opportunities in this ancient district of ore.