Modal composition and grain-size characteri stics, physical and mechanical propertie s of three samples of Archean gneisses of the Kola series from the depths of 6.8 to 8.4 km of the Kola Superdeep Borehole (KSDB-3) and two collections of their surface analogues were analysed. On the basis of a comparison of the petrographic characteristics of the borehole samples and analogues, it was found that not all analogues are equivalents of corresponding core samples completely. Mechanical properties of core samples are affected by depth of the core sample position in the borehole. This work forms part of the research in the frame of the INTAS Project No.314 "Geodynamics in the cross-section of the Kola superdeep"., Jiřina Trčková, Vladimír Šrein, Martin Šťastný and Roman Živor., and Obsahuje bibliografické odkazy