GEOENVIRONMENTAL CHARACTERIZATION OF THE SAN QUINTÍN MINE TAILINGS, CIUDAD REAL (SPAIN)

The abandoned San Quintín mining group (Ciudad Real) was operated by the Sociedad Minero-Metalúrgica de Peñarroya, and 515.300 tons of galena concentrates were obtained between 1888 and 1923. Two geophysical surveys, using electrical resistivity imaging (ERI) and ground-penetrating radar, as well as mineralogical and geochemical techniques have been used in order to obtain a geo-environmental characterization of the mine pond. The ERI has allowed us to determine both the general geometry of the pond’s substrate and a maximum thickness of the mine tailings of 12 m. Tailings are medium-to-coarse grained materials mainly composed of quartz, clay minerals, gypsum and feldspars. Neither acid mine drainage nor modification of their internal structure have been detected. The amount of ore minerals in the tailings have been greatly reduced because of their reworking. Joint application of geophysical and geochemical techniques has revealed as very useful for obtaining a complete characterization of abandoned mine deposits, previously to a future reclamation of these hazardous tailings.