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Two samples of mine wastes were selected from an abandoned deposit at the Natural Park Estero Domingo Rubio, in order to determine the fractionation and relative mobility of some heavy metals (Cd, Cu, Mn, Ni, Pb, Zn). The chemical partitioning of elements was conducted by a six-step sequential extraction scheme developed for Te-rich materials. The results showed high pseudototal concentrations of heavy metals (up to 3249 mgL1 Pb, 1670 mgL1 Zn and 625 mgL1 Cu). A large proportion of these potentially toxic metals are easily mobilisable at the present acidic and oxidant conditions, because most of them are bound to soluble and/or exchangeable phases (up to 84% Pb) and oxidisable phases (up to 91%Zn, 83% Cd and 71% Cu) ofthe wastes

The boundary between the Ossa Morena and the South Portuguese zones is outlined by the Aracena metamorphic belt. The main characteristics of this region of the Iberian Massif are divided into lithologic, structural, metamorphic, magmatic, geochemical, isotopic and experimental points of view and presented in this paper. The Aracena metamorphic belt is divided into two main domains: the oceanic domain is composed of MORB-derived metabasites (the Acebuches metabasites) and a former accretionary prism. The continental domain comprises aluminous gneisses and migmatites, calc-silicate rocks, leucocratic gneisses, marbles, amphibolites, syn- to post-tectonic noritic intrusions with high-Mg andesite (boninitic affinities) composition, as well as post tectonic acid-to-basic intrusive rocks. The Acebuches metabasites were firstly affected by a high-temperature/low-pressure event, which currently shows an inverted metamorphic gradient, and is related to SW verging thrusting. The thermal peak related to this metamorphic event displays an age gradient in such a way that older ages have been obtained towards the west. The lower half of the Acebuches metabasite pile was later affected by a mylonitic deformation and a retrometamorphism related to the Southern Iberian Shear Zone. Four ductile deformation phases have been defined in the continental domain: CD-D1 was related to the formation of km-scale recumbent folds. CD-D2 could be associated with an extensional collapse or a gravity spreading, and is coeval with a high-temperature/low-pressure metamorphic event that affected the continental domain and gave place to several migmatitic complexes. CD-D3 produced symmetric upright folds and CD-D4 generated south-verging thrusts and thrusts accommodation folds. The main characteristics of the Aracena metamorphic belt are interpreted as the result of a trench-trench-ridge triple junction evolution. According to the proposed model, the oceanic ridge-trench interaction led to the formation of a slab-free window beneath the continental margin, which provoked the upwelling of the underlying astenosphere and a subsequent thermal rebound. This triple junction migrated along the continental margin towards the east, which gave place to the generation of a high-temperature/low-pressure metamorphic belt in the contact between the Ossa Morena and the South Portuguese zones. El contacto entre las zonas de Ossa Morena y Sudportuguesa está subrayado por la banda metamórfica de Aracena. Las características principales de esta región del macizo Ibérico pueden considerarse desde distintos puntos de vista: litológico, estructural, metamórfico, magmático, geoquímica, isotópico y experimental, y así se presentan en este artículo. La banda metamórfica de Aracena está dividida en dos dominios principales: el dominio oceánico está formado por metabasitas derivadas de un MORB (las metabasitas de Acebuches) y por un antiguo prisma de acrección. El dominio continental incluye gneises y migmatitas alumínicos, rocas de silicatos cálcicos, gneises leucocráticos, mármoles, anfibolitas, intrusiones sin/post-tectónicas de noritas ricas en Mg (con afinidad boninítica), así como rocas intrusivas post-tectónicas de composición ácida a básica. Las metabasitas de Acebuches sufrieron, en primer lugar, un metamorfismo de alta temperatura/baja presión que, en la actualidad, presenta un gradiente metamórfico invertido, y que estaba relacionado con un cabalgamiento vergente al SO. El pico térmico asociado a este evento metamórfico muestra un gradiente de edad, de forma que las edades más antiguas han sido obtenidas en el extremo oeste. La mitad inferior de la pila metabasítica de Acebuches fue afectada posteriormente por una deformación milonítica y un retrometamorfismo asociados a la zona de cizalla Sudibérica. Cuatro fases de deformación dúctil han sido definidas en el dominio continental: la fase CD-D1 estuvo relacionada con la generación de pliegues recumbentes de escala kilométrica. La fase CD-D2 se puede asociar a un colapso extensional, y es contemporánea con un metamorfismo de alta temperatura/baja presión que afectó al dominio continental y generó diversos complejos migmatíticos. La fase CD-D3 produjo pliegues simétricos verticales, mientras que la fase CD-D4 dio lugar a cabalgamientos vergentes al sur a los que se asociaron pliegues de propagación. Las principales características de la banda metamórfica de Aracena se interpretan como el resultado de la evolución de un punto triple de tipo fosa-fosa-dorsal. De acuerdo con el modelo propuesto, la interacción entre la dorsal y la zona de subducción dio como resultado la formación de una ventana astenosférica bajo el margen continental cabalgante, lo cual provocó el ascenso de la astenosfera y el consecuente rebote térmico. Esta unión triple migro a lo largo del margen continental hacia el este, lo que generó un cinturón metamórfico de alta temperatura/baja presión en el contacto entre las zonas de Ossa Morena y Sudportuguesa.

In this work a detailed geological map of the graphite mineralizations of the Aracena Metamorphic Belt (SW Iberian Massif) is shown. Three types of mineralizations have been distinguished according to lithostratigraphic and structural criteria: 1) Stratiform deposits related to gneissic lenticular bodies embedded within a complex calc-silicate sequence 2)Veinlets of graphite cutting across mafic granulites; and 3) Disseminated graphite within gneisses and quartzites belonging to the Fuente del Oro series. Only the first type of mineralizations could have an economic interest. DGICYT. Gobierno de España-PB93-0064

As a consequence of the large mining operations occurred at Rio Tinto area (SW Spain) since prehistoric times, forests were demolished, rivers were polluted by heavy metals, sulphates and suspended particles, air was polluted by So2 producing acid rains and human health problems, wastes (slags, pyrite ashes, and other leaching materials) were storaged as great mountains, and landscape turned wilderness and inhospitable with many abandoned mining factories and ghost villages. Today, environmental problems derived from this old situation and present activities are a challenge for the Administration, ecologists and society, since the Rio Tinto area is the most contamined of Spain

Wollastonite is a relative newcomer to the industrial minerals market, which economic interest is determined by the acicularity of the crystals. In this work, a linear regression analysis of wollastonite crystal dimensions has allowed us to characterize the size and shape of the particles obtained by grinding at different times, in order to determine the grinding influence on the acicularity of mineral.

This paper describes the occurrence of auth¡genic gypsum on the flood plain of the Río Tinto, a river highly polluted by acid mine-drainage. Gypsum appears typically as isolated tabular crystals of selenite scattered within the muddy sediment, and associated with day minerals, quartz, feldspars and halite. Both field and experimental data strongly suggest that the gypsum precipitated authigenically on the mudflat as a result of the reaction of acidic sulphate waters with detrital and biogenic calcite locally supplied by unpolluted tributaries. Consequently, in this case the presence of authigenic gypsum could be used as a paleoenvironmental indicator of the stream contamination

Los componentes mineralógicos fundamentales de los sedimentos actuales del río Odiel son: cuarzo, feldespatos y filosilicatos. La asociación illita-clorita-caolinita refleja el carácter esencialmente detrítico heredado de los minerales de la arcilla. Por otra parte, la asociación de minerales pesados muestra la influencia de dife¬rentes áreas fuentes. El Odiel está extremadamente contaminado por metales pesados. La proximidad de importantes centros mineros de la Faja Pirítica tiene una gran incidencia sobre la concentración y distribución de Fe, Cu, Pb, Zn y Mn. Los sedimentos del estuario presentan algunas diferencias mineralógicas y geo-químicas importantes con respecto a los sedimentos típicamente fluviales. The mineralogical composition and the heavy metáis contení of recent sediments in the Odiel river have been investigated. Quartz, feldspar an phyllosilicates are the major constituents of the bulk sample. The illite-chlorite-kaolinite assembla- ge shows the inherited detrital character of the clay minerals. On the other hand, the heavy mineral associations indicate source areas. The river is very polluted by heavy metáis. The proximity of important mining centres has a strong influence on the concentration and distribution of Fe, Cu, Pb, Zn and Mn. The estuarine sediments studied have some mineralogical and geochemical fea¬tures which are different from that of typical river sediments.

Se describen las características geoquímicas, mineralógicas y petrográficas de los materiales pizarrosos de un sector de la Faja Pirítica y, en base a estos datos, se discuten sus condiciones de formación y evolución durante el metamorfismo. Finalmente, se analiza la incidencia de la mineralogía y de los factores texturales y microestructurales en la calidad de las pizarras como rocas industriales., The geochemical, mineralogical and petrographical features of slates from the Iberian Pyrite Belt (SW Spain) are studied. On the basis of these data, the origin and metamorphic conditions undergone by these materials are discussed. Finally, the infiuence of mineralogical, textural and microstructural factors on their use as industrial rocks (roofing slates) is estimated.