The coal mining in Petroşani Basin (South Carpathians, Romania) led to build up of huge sterile dumps. Some of them were planted with Hippöphae rhamnoides (sea buckthorn). The dump mineralogy studied by X-ray diffractions and microscopy showed quartz, calcite, potassium feldspars, and biotite. Comparative investigations carried out on these samples show a random arrangement in the mineral particles in the areas devoid of small trees. In the other areas, the majority of the minerals – mainly calcite and biotite - are adsorbed on plant root surfaces. This fact is proved by the X-ray elementary fluorescence analysis, which points out a faint increase of Ca and Mg contents for the samples originating from root soil and a slow decrease of quartz content. The genesis activity of the sea buckthorn is observed in the higher content of Ca and lower content of Mg in fruits compared with the average standard value, documenting that the dump soil is richer in calcium than in magnesium. The presences of the ascorbic acid in sea buckthorn fruits revealed in the thin layer chromatogram in sufficient amount indicate relative normal plant synthetic activity of organic substances, but running relatively slow due to humus scantiness. For accelerating the formation of a fertile soil, it would be useful to distribute aqueous dispersion of manure, which would lead to faster humus formation, needed for faster growing of planted small trees.