The waste of the tailings pond has a yellowish appearance, over 70-80 wt% consisting of fine and very fine particles. The dominant minerals are quartz, sericite, chlorite and pyrite, while sphalerite and biotite occur accidentally. Translucent crystal grains of presumed hydrated sulfates were identified as well. The pH is very low (mean of 3.1), as well as the abundance of the soluble fraction (mean less than 2.0wt%). Across the surface of the waste deposit, four sectors with specific geochemical properties were identified, using statistical analyses: (1) the northern and southern edges of the horizontal surface (C2), where the waste is the most susceptible to be removed and transported either by wind or by runoff; (2) the flat, horizontal sector C1, rich in Al, Mg, Mn, and K, where especially the silt and clay particles accumulate; (3) the sector C3 which overlaps the watercourse of the temporary stream, the latter being the main vector of mechanical and chemical removal and transport of waste towards the surrounding areas; (4) the sector C4, the richest in toxic trace elements, related especially to primary sulfides, less mobile because of their higher specific weight. The relation between this geochemical distribution and other properties of the tailings (e.g., mineralogy, grain size, abundance of soluble fraction, pH) suggested that the sectors C2 and C3 present the highest risk to the environment.