ORIGINAL ARTICLE Mineralogy and geochemistry of the Texeo Cu–Co mine site (NW Spain): screening tools for environmental assessment J. Loredo Æ R. A ´ lvarez Æ A. Ordo ´n ˜ez Æ T. Bros Received: 18 December 2006 / Accepted: 8 October 2007 / Published online: 23 October 2007 Ó Springer-Verlag 2007 Abstract The Cu–Co–Ni Texeo mine has been the most important source of Cu in NW Spain since Roman times and now, approximately 40,000 m 3 of wastes from mine and metallurgical operations, containing average con- centrations of 9,263 mg kg –1 Cu, 1,100 mg kg –1 As, 549 mg kg –1 Co, and 840 mg kg –1 Ni, remain on-site. Since the cessation of the activity, the abandoned works, facilities and waste piles have been posing a threat to the environment, derived from the release of toxic elements. In order to assess the potential environmental pollution caused by the mining operations, a sequential sampling strategy was undertaken in wastes, soil, surface and groundwater, and sediments. First, screening field tools were used to identify hotspots, before defining formal sampling strategies; so, in the areas where anomalies were detected in a first sampling stage, a second detailed sam- pling campaign was undertaken. Metal concentrations in the soils are highly above the local background, reaching up to 9,921 mg kg –1 Cu, 1,373 mg kg –1 As, 685 mg kg –1 Co, and 1,040 mg kg –1 Ni, among others. Copper con- centrations downstream of the mine works reach values up to 1,869 lgl –1 and 240 mg kg –1 in surface water and stream sediments, respectively. Computer-based risk assessment for the site gives a carcinogenic risk associated with the presence of As in surface waters and soils, and a health risk for long exposures; so, trigger levels of these elements are high enough to warrant further investigation. Keywords Abandoned mining Á Arsenic Á Copper Á Screening methods Á Risk assessment Introduction A major outstanding environmental problem is that of abandoned mine sites, which usually offer a legacy con- stituted of abandoned underground and surface mine facilities (shafts, galleries, and external buildings) and spoil heaps that might become pollution sources. Wastes improperly stored, leachates, and mine effluents have in many cases, a considerable impact on the environment because of the mobility of specific metals and metalloids. Due to the particular potential health risks that some metallic and non-metallic elements can pose to humans and ecosystems, considerable interest and concern has been focused on the impact associated with mining and smelting activities upon wastes, soils, and water. Pollution associ- ated with base metal mining and smelting is abundantly reported in the literature (Davies 1983; Salomons 1995; Allan 1997; Plumlee 1999; McMartin et al. 1999; Ashley et al. 2003; Kelley and Kelley 2003); so, metal mobiliza- tion from spoil heaps constitutes the main objective of the study presented here. Waste materials stocked in mine spoil heaps are usually constituted of barren rocks, low grade ore and occasionally, wastes from smelting operations when these are located at the mine site. Variability of waste materials creates an internal heterogeneity structure characterized by wide variations in grain size, density and mineralogy. Depending on the mineralogical characteristics, wastes often have a moderate to high content of metals and metalloids, which can be dispersed far away in the form of leachates pro- duced by percolation of rainwater and surface runoff J. Loredo Á R. A ´ lvarez Á A. Ordo ´n ˜ez Á T. Bros Departamento de Explotacio ´n y Prospeccio ´n de Minas, University of Oviedo, Oviedo, Spain A. Ordo ´n ˜ez (&) E.T.S. Ingenieros de Minas, c/ Independencia 13, 33004 Oviedo, Asturias, Spain e-mail: aoalonso@uniovi.es 123 Environ Geol (2008) 55:1299–1310 DOI 10.1007/s00254-007-1078-y