Black shales of the Early Paleozoic age are widespread in Sweden, forming part of the Baltic paleobasin, sediments of which are also known in Estonia and Leningrad region of Russia. Black shales accumulate chemical elements, contents of which exceed the Clarke values: Re - 700, Ag - 12, U - 10, Mo - 10, Pd - 4.7, V - 4.2, Pt - 3.5, Au - 3 times. Colloid-salt fraction (nanofraction) with particle size of less than 1000 nm was extracted with water from the rock and analyzed by ICP MS method. Accumulation coefficient of chemical elements in comparison with the total analysis is for Pd - 47, for Co, Ni, Cd - from 15 to 31, for U, Cu, Zn and Re - from 3 to 10. The geochemistry of black shales is similar, but different in chemistry of nanofractions, which can be an important distinction of deposits. Water-soluble mobile forms of elements can be washed out of the rock and migrate to the environment, creating the increased natural geochemical background of the area.