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do not oibjeotiiV€iy reflect the real outlays redated to the drilling of rocks of vardous typas, accardimg to the classłfkation. This, among others, as proved by a eansiderable differentiation in mechanika! progress in rocks of the same category. The present author suggests to wonk out a new dassłfdoation especially based on the research of drillability of rocks. In addiition to this be gives a short review of lithological types and categaries of rocks according to the abligatory dŁassiftkration of .rocks that occur in the indto-idoial geological fiarmations withdn the Foldsh Dowlahd area. It also appears that so dóififerentiated prices between the oore drillding and the oorełess drilling are unjuBidifded. There are given examples where rocks characterized by liow dciUabdlity have been pianced by diamond oore drill at the <Lntervals destinated for drillimg usinsg normal bits, and the results have naturally been better than when drilling with bits.

Taking dnto accouint the generał tendency to diminish the scope of oore recovery to dmtroduce modem drilling technology the author emphasizes that the sdgnif kanoe of the dribdwg coras obtadned by the Geological Institute from the investigation borę holes ds oonsdderalble, and that this geotaglcal materiał camnot be replaced by other auxiliary research methods. The soope of ooring in borę holes madę at present by the Geological Institute naanges fnam 15 to 25 per cent.

During ithe analysis of the performance of deep borę holes attemtksi has been paid to consdderalble production reserves relaited to the elimiination of standstills caused by failures and fishimg works (Table 1), and to ecomomical advantages whkh can be got by the geałogdcal enterpnrses. Emphasdzed are coordimation of works, and introduction of new methods (partkularly samplers) which cut down time of samplimg after dmiłłmg process.

The best results, as oanoems deep drillings, were noted — within the Central Office of Gealogy — by the Geological Enterprise Wareaw, which dn June 1972 completed the borę hole Kościerzyna (5202 m), the deepest one in. the Polish Dowland area. This enifcerprdse broedly imtroduced the laboratory servke af deep drillings, installing socne etatdcnary and movatoIe laboratories of ”Geoservdce” type, eąuippefd with research Instruments of French production. The geological servke of drillings is carried on by the geologists of the geological supervMon, for the most part by the workars of the geological enterprises and by the geologists of the geological inspection of the Gedogical Institute.