Weathering – soil forming processes were studied on the spoil heaps of an abandoned pyrite mine in Wieściszowice (German: Rohnau, Lower Silesia, Poland). These heaps of waste material were formed during the 19th century, with the mining ceasing in 1902. The material was not homogenous texturally (loam and sandy loam layers) and did not show coloured genetic horizons. In the soil formations, the humus horizon was approximately 10 cm deep, and contained approximately 10% of organic matter in various stages of decomposition. The reaction in the whole soil profiles was acidic (pH approx. 4.0), and composition quartz, feldspars, chlorites and micas prevail in the mineral. Pyrite was not observed among the minerals, although secondary sulphate minerals were found such as: gypsum, jarosite, fibroferrite and iron oxides (mainly goethite). Clay minerals included chlorite, illitic material (K-mica and Na-mica), kaolinite and smectite as well as mixed-layered minerals of the mica/smectite type.