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Mercury mineralizations in the Almaden district can be grouped in two main categories: i) strata-bound mineralizations hosted in Criadero quartzite (Lower Silurian) and ii) veins and stockworks in Silurian and Devonian hosting rocks. The 39Ar/40Ar dating of illite, probably related with the hydrothermal activity responsible of the second type of mineralizations, yields 361 ± 2 Ma. This age is some 25-50 Ma older than the age of granitic intrusions in the area, and could be the age of the epigenetic mercury mineralizations

New petrographic and chemical data on the Garlitos pluton and other associated igneous rocks in the Almadén area have shown a high-K calc-alkaline character and clear simiarities with other calc-alkaline granitoids, in particular the lithotypes dominant in the Los Pedroches batholith. Similarities include petrographical, mineralogical and chemical features, as well as a number of metamorphic xenoliths, suggesting that igneous rocks were generated from similar sources and emplaced through similar crustal segments.

After seven years of experience in a project, controlled from its beginning by the C.O .U. (University Orientation Academic Year) coordination group of Castilla-La Mancha University, now we present the results of the modifications for the subject "Geology " recommended by the Education & Science Ministry in the program development and the university entrance examinations

This paper deals with the preliminary study of the possible ceramic applications of wastes generated in the coal mines of Puertollano (Ciudad Real - Spain). The mineralogical and chemical composition, as wells as the technological tests, of shales Interbedded with the coal, point that these shales are suitable raw materials for the ir use in the ceramic tile Industry of white or light colored types

This paper deals with the preliminary study of the possible ceramic applications of wastes generated in the coal mines of Puertollano (Ciudad Real - Spain). The mineralogical and chemical composition, as wells as the technological tests, of shales Interbedded with the coal, point that these shales are suitable raw materials for the ir use in the ceramic tile Industry of white or light colored types

Chemical composition of igneous pyroxenes in the basic rocks from the Almadén syncline shows important differences between basaltic lavas and olivine diabases (Silurian to Devonian in age), and quartzdiabases on the other hand. Higher CaO, Al203 and Ti02 and lower Si02 contents in pyroxenes from the first group are characteristics of alkaline magmas. Lower CaO, Al203 and Ti02 and higher Si02 in pyroxene from quartzdiabases are indicative of a subalkaline (tholeiitic) affinity. These chemical differences are consistent with whole-rock chemistry, with higher Nb/Y and (La/Lu)cn ratios in the first group. Alkaline and tholeiitic magmatism are a consequence of different partial melting rates, lower for the alkaline liquids

Chemical composition of igneous pyroxenes in the basic rocks from the Almadén syncline shows important differences between basaltic lavas and olivine diabases (Silurian to Devonian in age), and quartzdiabases on the other hand. Higher CaO, Al203 and Ti02 and lower Si02 contents in pyroxenes from the first group are characteristics of alkaline magmas. Lower CaO, Al203 and Ti02 and higher Si02 in pyroxene from quartzdiabases are indicative of a subalkaline (tholeiitic) affinity. These chemical differences are consistent with whole-rock chemistry, with higher Nb/Y and (La/Lu)cn ratios in the first group. Alkaline and tholeiitic magmatism are a consequence of different partial melting rates, lower for the alkaline liquids

Sediments from Castilseras reservoir (Almadén) were collected to assess the potential environmental hazards associated with the availability of Potentially Toxic or Harmful Elements (PTHE) in this freshwater environment. PTHE concentrations in sediments were investigated using a four step (F1–F4) Sequential Extraction Procedure (SEP) and the results were evaluated using Principal Component Analysis (PCA) and different risk indexes and criteria. Considering the fractions results and the PCA treatment, two groups of elements can be differentiated in the easily leached by weak acids fraction F1 and these indicate the presence of sulfate and secondary precipitates of carbonates as the main sink for easily accessible metallic elements. In reducible fraction F2, chemical analysis revealed a significant relationship between the majority of the analyzed elements and the Fe oxy-hydroxides, with the exception of Co, Hg and Ni, which are preferentially associated with Mn oxy-hydroxides. In the oxidizable fraction (F3), a significant relationship between Cu, Fe, Hg and Zn (representative metals of the existing ore deposits) and sulfides/organic matter was observed. The environmental assessment based on the aforementioned criteria provides risk levels varying from moderate to high. The risk appears to be higher near the dam, where the higher PTHE levels in sediment are due to a selective accumulation of fine-grained particles.

Sediments from the Castilseras reservoir, located downstream on the Valdeazogues River in the Almadén mercury district, were collected to assess the potential contamination status related to metals(oids) associated with river sediment inputs from several decommissioned mines. Metals(oids) concentrations in the reservoir sediments were investigated using different physical and chemical techniques. The results were analyzed by principal component analysis (PCA) to explain the correlations between the sets of variables. The degree of contamination was evaluated using the enrichment factor (EF) and the geoaccumulation index (Igeo). PCA revealed that the silty fraction is the main metals(oids) carrier in the sediments. Among the potentially harmful elements, there is a group (Al, Cr, Cu, Fe, Mn, Ni, and Zn) that cannot be strictly correlated to the mining activity since their concentrations depend on the lithological and edaphological characteristics of the materials. In contrast, As, Co, Hg, Pb, and S showed significant enrichment and contamination, thus suggesting relevant contributions from the decommissioned mines through fluvial sediment inputs. As far as Hg and S are concerned, the high enrichment levels pose a question concerning the potential environmental risk of transfer of the organic forms of Hg (mainly methylmercury) from the bottom sediments to the aquatic food chain.

The distribution of heavy metals in plants growing in soils from active and abandoned mining areas is of scientific significance as it allows one to recognize their ability to survive in a hostile environment and to provide useful indications for phytoremediation operations. In this work, soils developed in the former Hg-mining area of Abbadia San Salvatore (Tuscany, Central Italy) were analyzed for total, leached Hg, % of organic- and inorganic-related Hg. The dehydrogenase enzyme activity (DHA) was also measured with the aim to evaluate the status of the soil, being characterized by high Hg content. Eventually, the concentration of Hg in the different parts of the plants growing on these soils was analyzed. The soils showed Hg content up to 1068 mg kg - 1 and in most of them is dominated by inorganic Hg (up to 92%). The DHA concentrations were < 151 µg TPF g - 1 day - 1 , suggesting that the presence of Hg is not significantly affecting the enzymatic soil activity. This is also supported by the bioaccumulation factor (BF) that is < 1 in most of the studied plants. Generally speaking, the plant leaves appear to be one of the main pathways of Hg uptake, as also observed in other mining areas, e.g. Almaden (Spain), suggesting that particulate-Hg and Hg 0 are the main forms entering the plant system, the latter derived by the GEM emitted by both the edifices hosting the roasting furnaces and the soils themselves.