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Papers by Javier Garcia-Guinea

Arbor Ciencia Pensamiento Y Cultura, 2013

Revista chilena de historia natural

Chemosphere, Jan 8, 2015

Scorodite-rich wastes left as a legacy of mining and smelting operations pose a threat to environ... more Scorodite-rich wastes left as a legacy of mining and smelting operations pose a threat to environmental health. Colloids formed by the weathering of processing wastes may control the release of arsenic (As) into surface waters. At a former mine site in Madrid (Spain), we investigated the mobilization of colloidal As by surface runoff from weathered processing wastes and from sediments in the bed of a draining creek and a downstream sedimentation-pond. Colloids mobilized by surface runoff during simulated rain events were characterized for their composition, structure and mode of As uptake using asymmetric flow field-flow fractionation coupled to inductively plasma mass spectrometry (AF4-ICP-MS) and X-ray absorption spectroscopy (XAS) at the As and Fe K-edges. Colloidal scorodite mobilized in surface runoff from the waste pile is acting as a mobile As carrier. In surface runoff from the river bed and the sedimentation pond, ferrihydrite was identified as the dominant As-bearing collo...

AMBIO A Journal of the Human Environment

The mineralogical composition of geological materials of Fuertescusa have been determined by mult... more The mineralogical composition of geological materials of Fuertescusa have been determined by multipurpose techniques. The Weal and Utrillas facies were studied in detail as wellas their geological setting in the Cordillera Iberica together with their economical possibilities.

Deposits and principal physico-chernical characteristics of sorne Spanish topazes are described. ... more Deposits and principal physico-chernical characteristics of sorne Spanish topazes are described. From the chernical point of view it is 10 be noted the high fluorine contenl (18.90-20.32 %) of these topazes, that can be correlated well with other physical propenies and 10 be related with the high fluorite percenlages of the paragenesis. Topazes occur in pegrnatites, greisen and hymotermal deposita, usually witb fluorite. The outcrops studied present a limite amount of topaz, hul frorn two of tbem (Valle de la Serena and Merida) beautiful faceted gems can be obtained of a transparency, low fracturation and feeble blue-green co-louration very suitable. Key words: Gemstones-Topaz-Greisen-Spain RESUMEN. -Se describen las carac-terísticas fisicoquímicas y los afloramientos de los principales topacios españoles. En su composición, destacan los elevados conte-nidos en fluor (18.90-20.32 %). Este dato, se correlaciona bien con el resto de las constantes físicas y desde el punto de vista gen...

ABSTRACT En el complejo minero "San Nicolás", situado al SW de Valle de la Sere... more ABSTRACT En el complejo minero "San Nicolás", situado al SW de Valle de la Serena, se han encontrado topacios de indudable interés gemológico. Los topacios se han formado durante un proceso de greisenización ocurrido tras la intrusión de granitos en una serie cuarcílico-pelítica. Están asociados a cuarzo, feldespatos, fluorita y lepidotita y otras mineralizaciones metálicas especialmente ricas en W y Bi. Las constantes cristalográficas de estos topacios son: ao = 4,655 1 (±3) A; bo = 8,8062 (± 6) A; co = 8,3953 (± 5) A. Los índices de refracción son: na = 1,617; nb = 1,6 18; ny = 1,625, 2Vy = 64°, G = 3,556. La formula crisialoquímica es la siguiente: (Si 3.96 Al0•04) O16 (Al 8.02 Fe2+0.005 Ca0.004 • Mg0.004 (F 7,38 OH0.6) Existe una buena correlacion entre las propiedades físicas determinadas, parámetros cristalográficos y % de F. ABSTRACT Topares of gemological interest have beeo fouod io th e complex ore field named "San Nicolás", located at SW of Valle de la Serena. Topazes Corrned during a greisenization process occurred after the intrusion of granitic masses in a quartzitic·pelitic series. This facies oí greisen is composed mai nly by quartz, felspars, lepidoli te and fluorite and contains ore minerals, especially W and Bi ores.

Spectroscopy Letters, 2011

The Science of The Total Environment, 2003

Romans, Jews, Arabs and Christians built the ancient city of Toledo (Spain) with bricks as the ma... more Romans, Jews, Arabs and Christians built the ancient city of Toledo (Spain) with bricks as the main construction material. Manganese micro-nodules (circa 2 µm in diameter) have grown under the external bio-film surface of the bricks. Recent anthropogenic activities, such as, industrial emissions, foundries or traffic and housing pollution have further altered these old bricks. The energydispersive X-ray microanalyses (XPS) of micro-nodules shows Al, Si, Ca, K, Fe and Mn, with some carbon species. Manganese atoms are present only as Mn 4+ (pyrolusite phase, MnO 2 ) and iron as Fe 3+ (FeOOH-Fe 2 O 3 mixtures). The large concentration of algae biomasses of the River Tagus and the Torcón and Guajaraz reservoirs suggest manganese micro-nodules are formed either from water solutions rich in anthropogenic MnO 4 K in a reduction environment (from Mn 7+ to Mn 4+ ) or by oxidation mechanisms from dissolved Mn 2+ (from Mn 2+ to Mn 4+ ) linked to algae biofilm onto the ancient brick surfaces. Ancient wall surfaces were also studied by scanning electron microscopy (SEM-EDS) and Xray diffraction (XRD). Chemical and biological analyses of the waters around Toledo are also analysed for possible sources of manganese. Pyrolusite micronodules on ancient brick walls are good indicators of manganese pollution.

Naturwissenschaften, 1998

Journal of the American Ceramic Society, 2005

Time-dependent natural weathering processes suffered by historic bricks in Toledo (Spain) improve... more Time-dependent natural weathering processes suffered by historic bricks in Toledo (Spain) improve their physicomechanical properties by porous infill with gypsum, ettringite and mainly calcite. Both, these bricks and their experimental replica bricks, made from the original calcareous clays fired at the probable historical temperatures (700º -900ºC), have been analyzed by X-ray diffraction, optical and scanning electron microscopy, mercury intrusion porosimetry and ultrasound velocities to compare pore structure and strength evolution by mineral cementation. The resultant microstructure and mineral fillings depend on brick calcareous composition and firing temperature, the brick location environment, burial, indoor or outdoor walls, the lime-based joint mortars and coat plasters and infiltration waters.

Geological Magazine, 1999

Environmental Geology, 2006

The discovery of the giant Geode of Pulpı´(Almerı´a, Spain) was considered as an important highli... more The discovery of the giant Geode of Pulpı´(Almerı´a, Spain) was considered as an important highlight in the geological heritage of Spain. Projects developed for their conservation were immediately initiated with legal figures of protection and tourist projects. The Geode has a tourist interest, which must be tempered by environmental restrictions limiting the public visits. First results demonstrate that a continuous visit of two or three people for more than 10 min provokes the appearance of condensation and risks corrosion of the gypsum crystals. In addition, the electron microprobe analyses confirms (1) the hydrothermal phases of iron-manganese in carbonated host rock; (2) the presence of sulphides with Fe-Zn-Pb-Ag-Sb-Cu-Hg-As-Te-Se; and (3) Ba, Ca, and Sr sulphates with mercury traces. The present proposal to label the geode and the mining environment as geological-natural heritage is feasible, although any tourist adaptation must not permit visits to the geode indoor and Hg levels must be controlled.