The purpose of the study is to identify some mineralogical and geochemical features of the weathering products from the waste dumps resulted after the quarrying works of Negoiul Românesc (Călimani) as well as their impact on the environment. The study was carried out on products of limonitization (goethite, hematite), argillic products (beidellite, illite, kaolinite, montmorillonite) and on samples of surface water (puddles developed on the top of the waste deposits). Leachates of argillic products induce in the environment an obviously lower pH (pH = 2.52-4.25), than the solutions emerged through leaching of limonitization aggregates (pH = 5.99-6.17). Chemical features of the small puddles developed onto the upper part of quarry waste deposits suggest that, except for pH, they do not represent a key risk factor to the environment. Argillic wastes act as a barrier that prevents infiltration of contaminated surface water.