The area of the Deputatskoye deposit, where drilling was carried out, is composed of lithologically monotonous sediment strata dislocated in large gentle folds of sub latitudinal and northeastern strike. In terms of physical and mechanical properties that determine the choice of diamond tools, the rocks composing the deposit can be divided into three main groups: 1) heavily crushed, often sheared medium and fine grained sandstones and sandy clay shales cemented with calcareous material and ice, VIII IX categories of drillability; 2) sandy clay shales of VIII category of drillability; 3) dense silicified, in some places hornfelsed fine grained low abrasive sandstones of X XI categories of drillability.