The article considers some specific peculiarities of metasomatically altered rock of Svetloye gold and silver field , which is situated in Okhotsk region of Khabarovsk Territory. Enclosing rock of ore zones of the field under consideration are lava and tuff of andesite and andesite-dacitic, which are altered in all parts in the result of hydrothermal-metasomatic processes. At the field the following types of metasomatosis are displayed: propylitization, secondary silification, and argilization. Each type is characterized by own origination conditions – alkali composition of hydrothermal fluids and the temperature of their origination. The characteristics of physical and mechanical properties of field rock is examined, the regularities in strength characteristics reduction are defined by means of “weakening” minerals presence in rock, the regularities in the alternation of properties depending on the type of metasomatosis and the distribution of minerals in the cut of the field. With the purpose of defining the peculiarities of physical and mechanical properties alternation, the analysis of the results of field rock mineral composition and physical and mechanical properties determination is fulfilled. The regularities stated are important at the solution of the problem of the mineral stripping, the degree, character, and type of mine workings support.