Mercedes Suarez

• PhD
• Professor (Full) at University of Salamanca

This study focused on a detailed mineralogical and crystal-chemical analysis of Mg-smectites from four bentonite samples from Turkey. Mg-rich smectites, mainly associated with alkaline and evaporitic depositional conditions, are formed in environments such as salt lakes, brine springs, and sabkhas, as well as in hydrothermal systems, in some cases...

This work focuses on the study of the trace elements allocation in smectites throughout the statistical analysis of geochemical data corresponding to a very wide group of pure or almost bentonite samples. Data of trace elements contents corresponding to both analysed samples and bibliographic references were treated with different statistical analy...

Coal samples from the Jarando, Tadenje and Progorelica mines and organic-rich shale samples from the Piskanja boron deposit, all located in the Tertiary Ibar Basin, were studied using several methods such as transmitted light microscopy, X-ray powder diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS)...

A geological, mineralogical, and geochemical characterization of the Tamame de Sayago (Zamora, Spain) deposit was carried out with the aim of knowing the conditions that facilitated the genesis in the same deposit of kaolinite and smectites. The alteration processes affecting a Variscan granite were deduced throughout the study of a very wide group...

In this study, a new genetic interpretation of the Mg-bentonite deposits from the Tajo Basin is given through a high-resolution transmission electron microscopy study. These bentonites, belonging to the Green Clays and Pink Clays lithostratigraphic units, are afforded by the sum of processes occurring during the weathering of parent rocks and the e...

Palygorskite is a mineral used in a wide number of industrial sectors. Currently, there are hundreds of studies in which palygorskite is a part of different nanocomposites and bionanocomposites. The surface properties are essential for these applications, and in this work, an in-depth revision of these properties is done, showing that the high vari...

The Dueñas Clay Formation is considered an example of a deposit of lacustrine continental origin. It is formed mainly by overconsolidated clays and includes feldspathic arenites, and clayey and silty levels; however, in geotechnical projects it is considered a clay unit and treated as a whole. The structure of each level was assessed in the field,...

Mineralogical characterization of kaolinite from Tamame de Sayago (Zamora) through VNIR-SWIR spectroscopy.

This comparative study on a very wide group of samples shows that the crystal size and crystalline defects of smectites influence microporosity of bentonite considerably more than previously considered. The smectite crystals and surface properties, including microporosity and micropore volume, were studied using high resolution transmission electro...

Maya Blue is a pigment found in different archaeological sites of different cultures from Mesoamerica and also in colonial buildings in Mexico and Cuba. This pigment is made from a thermally treated mixture of indigo and palygorskite. In this paper, pigment samples from Aztec and non‐Aztec archaeological sites as well as reference Yucatecan palygor...

Samples of The Miraflores Basalt sub-volcanic rocks (Miocene Late Basalt Formation) collected from different quarries on the Isthmus of Panama and several samples collected from the excavation of the third set of locks in the New Panama Channel were characterised in this study. All rocks studied had similar petrological and mineralogical characteri...

The Eastern Galicia Magnetic Anomaly is the best studied anomaly of the Central Iberian Arc. This is due to its location, on the Lugo‐Sanabria gneiss dome, and to the fact that its source rocks crop out in the Xistral Tectonic Window. Multiple studies of this anomaly have been carried out, but still, new results keep on shedding light on its unders...

A mineralogical characterization of a group of bentonite samples was done by X-ray diffraction (XRD), chemical analysis by inductively coupled plasma mass spectroscopy (ICP-MS), and visible-near infrared and short-wave infrared spectroscopy (VNIR-SWIR). As tested by XRD, all samples are very pure, composed mainly of smectites with very small amount...

A detailed characterization of a group of kaolin samples rich in some minerals of the kaolinite group was done. The mineralogical and structural characterization was conducted by X-ray diffraction (XRD) together with the study of the spectroscopy response in visible-near infrared and short wave (VNIR–SWIR), and the main objective was the determinat...

The understanding of the structural formula of smectite minerals is basic to predicting their physicochemical properties, which depend on the location of the cation substitutions within their 2:1 layer. This implies knowing the correct distribution and structural positions of the cations, which allows assigning the source of the layer charge of the...

The third set of locks of the Panama Canal is one the most impressive civil infrastructures in the world. Its construction, however, was delayed by two years incurring cost overruns in billions that were mainly related to the use of the local basalt as the raw material for concrete production. The rapid degradation during the construction of an app...

Lacustrine strata record long-term variations in climatic and tectonic perturbations during orogen evolution. Here we use the sedimentological record of the early to middle Miocene intramontane lacustrine Pranjani Basin (Serbia) to study tectonic and climatic variations during the evolution of the Dinaridic orogen. Our study focuses on a Mg-clay-be...

Palygorskite is a clay mineral whose structure has not been successfully deciphered, even considering the simultaneous presence of the orthorhombic and monoclinic phases within the same sample. An interesting question, which has barely been considered until the moment to explain the difficulty of the resolution of its structure, is whether the fibr...

p>The mineralogical analysis was carried out through the spectral properties developed by samples of soils and sediments from the northwestern edge of the Duero Basin. The absorptions produced by the oxides and Feoxyhydroxides (mainly hematite and goethite) are located in VNIR zones (400-1200 nm), while the absorption bands that are present in the...

A review and a synthesis of the geological, mineralogical, and crystal chemical data available in the literature on active Spanish bentonitic exploitations were done, and at the same time, new data are provided from a set of representative samples from these deposits. They were located in three different areas with different geological origins: (1)...

A comparative study of the unidimensional compressibility of two clays of continental origin but with different geological history is presented: the Armuña Clay and the Viso Clay. The former is a quaternary deposit of smectite and illite, with very high plasticity; the latter is a miocene overconsolidated clay of intermediate plasticity and with le...

A representative group of palygorskites from the six most important Spanish deposits and six other occurrences were studied comparing their mineralogy, textural features, crystal-chemistry, and surface properties. These palygorskites have different geological origin: (1) sedimentary in large Tertiary continental basins, (2) hydrothermally altered v...

The Tajo Basin is one of the richest in Mg-clays known around the world. Mg-bentonites, kwon as pink clays and green clays, alter in the Intermediate Unit of the Miocene sediments. In this work, a new approach to the genesis of these bentonites is performed by studying for the first time the biomarkers present in these clays in relation to the mine...

In this study we analyze in detail a palygorskite from Palygorskaja. This palygorskite is situated in the context of the existing studies using X-ray powder diffraction analysis. Moreover, a novel microdiffraction study on a small bunch of fibers shows highly structured 2D diffraction patterns that allow to decipher some information on the microstr...

This paper shows that clay minerals, sepiolite and palygorskite collected from Torrejón El Rubio and Vallecas, Spain, respectively, altered the expression of four, namely, pro-inflammatory cytokines: interleukins IL-1 and IL-6, tumor necrosis factor (TNF-α), and interferon gamma (IFN-γ) as determined using a 12-O-tetradecanoylphorbol-13-acetate mod...

Evidence of crystallization by particle attachment in synthetic materials is described in numerous contributions. However, efforts to establish the contribution of the particle attachment mechanism to inorganic crystallization in natural environments have barely begun. Here, we show, for the first time, evidence that confirms oriented particle atta...

The Upper Ediacaran detrital succession in the Cantabrian Zone shows geochemical and mineralogical changes resulting from sub-Cambrian weathering during the Late Ediacaran worldwide sea-level fall. Relative to the unaltered rocks the altered ones show crosscutting rubefaction of varying thickness and remarkable increase in illite, K 2 O, Rb and Cs...

Sepiolite and palygorskite have shown beneficial health effects but understanding human cell-clay interactions has yet to become unveiled. This paper reports on the effects of sepiolite (Vallecas, Spain) and palygorskite (Torrejon El Rubio, Spain) on the infiltration of human blood leukocytes to an infiltration site. Quantification of human blood l...

With the purpose of determining how geological processes affect the mechanical behavior of overconsolidated clays of continental origin, reconstituted, sedimented and natural samples of the Viso Clay have been studied under unidimensional compression. When sedimented, the clays adopt an structure which strength the soil, but its effect disappears w...

El Cuquero es un yacimiento de época visigoda, localizado en la parte noroccidental de la península Ibérica, cuya cronología ha sido establecida en torno al siglo VI. El asentamiento ha proporcionado un pequeño aunque homogéneo conjunto cerámico compuesto mayoritariamente por cerámica común y común de cocina, si bien a partir del examen macroscópic...

Quantitative phase analysis (QPA) of clayey materials using X-Ray diffraction data has always been a challenge. While quantitative methods based on Rietveld analysis offer excellent results for non-clay minerals, they become problematic when high crystallochemical and order degree variations are present in the phases, as is the case of most clay mi...

Keywords: Balearic Promontory bedded unit betic corridor evaporites Messinian Salinity Crisis Primary Lower Gypsum The Messinian Salinity Crisis (MSC) was a major ecological crisis affecting shallow and deep-water settings over the entire Mediterranean basin. However, the evolution of the MSC and its ecological impacts have mainly been explained on...

A sepiolite from Grant County (USA) was studied with two objectives. First, from a purely methodological perspective, a comparative micromorphological study was conducted using two imaging techniques: high-resolution transmission electron microscopy (HR-TEM) and atomic-force microscopy (AFM). The second objective was to determine whether the struct...

A detailed microscopic study of sepiolite and palygorskite natural samples reveals that independently of the fiber length they all are composed of other minor width fibers until the minor units or the true crystals. They are prismatic crystals elongated along [001] with rhombus-like morphology in cross section, designated laths. Although their leng...

A compositional gap between sepiolite and palygorskite has long been accepted even though they have similar structures, but recent studies found that such a gap does not exist and that the compositional series is continuous between them. If this is true, intergrowths between these two minerals should exist. The purpose of the present study was to d...

The fibrous morphology, the small particle size, and the presence of tunnels and channels in their structure give sepiolite (Sep) and palygorskite (Pal) a large specific surface area (SSA). The surface properties vary greatly among different Sep or Pal deposits because they are strongly conditioned by their textural and microtextural features (size...

A comparative study of a wide collection of sepiolites (22 samples from different locations, including samples coming from the greatest deposits of sepiolite in the world) was made with the aim of understanding the real variability of the surface properties in sepiolite. The samples have been studied by XRD, Electron Microscopy (TEM and SEM) and th...

Maya blue is an organo-clay artificial pigment composed of indigo and palygorskite. It was invented and frequently used in Mesoamerica in ancient times (eighth to 16th centuries). We analyse in this paper one of the characteristics of Maya blue that has attracted the attention of scientists since its rediscovery in 1931: its high stability against...

Construction on expansive soils can generally be resolved using piles. Where shallow foundations are used in these materials, the swelling pressure should be determined and the foundations designed to provide a greater pressure to counteract this. Clearly, it will also be necessary to determine the capacity of the ground to take this load. The pape...

The structure and chemical composition of sepiolite and palygorskite are known from the first half of the twentieth century. Ideal palygorskite Si8O20(Al2Mg2)(OH)2(OH2)4⋅H2O)4 has dioctahedral character, and sepiolite Si12O30Mg8(OH)4(OH2)4(H2O)8 is a pure trioctahedral mineral. In the two minerals, isomorphic substitutions in both tetrahedral and o...

Maya blue is an artificial pigment fabricated by the Maya in the early first millennium AD. The pigment was used in Prehispanic times from the southern Maya region to most Mesoamerican cultures. Maya blue is made from indigotin mixed with palygorskite. This light blue pigment is surprisingly resistant to degradation in adverse environmental conditi...

abStRact Twenty sepiolites of known composition from different origins were analyzed to quantify the variability in structural parameters and its possible relationships with composition and morphology. Morphology SEM analyses led to classify the sepiolites into several groups, beyond the two simple macroscopic or clay groups. X-ray powder diffracti...

abStRact Twenty sepiolites of known composition from different origins were analyzed to quantify the variability in structural parameters and its possible relationships with composition and morphology. Morphology SEM analyses led to classify the sepiolites into several groups, beyond the two simple macroscopic or clay groups. X-ray powder diffracti...

The mixed dioctahedral-trioctahedral character of Mg-rich palygorskite has been previously described by the formula yMg5Si8O20(OH)2(OH2)4·(1-y)[xMg2Fe2(1-x)Mg2Al2]Si8O20(OH)2(OH2)4, where y is the trioctahedral fraction of this two-chain ribbon mineral with an experimentally determined upper limit of y ≈ 0.5 and x is the FeIII content in the M2 sit...

Samples from IODP Site U1314, drilled in the Gardar Drift formation (subpolar North Atlantic), were studied to determine which processes mainly rule terrigenous sedimentation from continents in this area and to fingerprint the source of such lithic material. For this purpose, we performed a geo-chemical and mineralogical study using total digestion...

Many studies of the chemical composition of sepiolite and palygorskite have been carried out using analytical electron microscopy (AEM). According to the literature, a compositional gap exists between sepiolites and palygorskites, but the results presented here show that they may all be intermediate compositions between two extremes. The results of...

New chemical and structural data on sepiolite-falcondoite in garnierite veins from the Falcondo Ni-laterite deposits, central Dominican Republic, are reported. Samples of Ni-sepiolite-falcondoite vary in colour from whitish green to green depending on the NiO content (wt.%) and the amount of silica present. The texture is normally schistose and fri...

The heating process (30–200°C) of a palygorskite-indigo mixture has been monitored in situ and simultaneously by synchrotron powder diffraction and Raman spectroscopy. During this process, the dye and the clay interact to form Maya blue (MB), a pigment highly resistant to degradation. It is shown that the formation of a very stable pigment occurs i...

Palygorskite is a rare clay mineral used by the ancient Mayas for fabricating the Maya blue pigment and for other purposes. It seems to have been obtained from a restricted area in the Yucatán peninsula where important archaeological sites are found. Geological samples from different localities in this area show a high content in palygorskite, indi...

The OH speciation of 18 palygorskite samples from various localities were evaluated by near infrared spectroscopy (NIR) and compared to the corresponding octahedral composition derived from independent, single-particle analytical electron microscopy (AEM). NIR gives evidence for dioctahedral-like (AlAlOH, AlFe(3+)OH, Fe(3+)Fe(3+)OH) and trioctahedr...

New chemical and structural data on sepiolite-falcondoite in garnierite veins from the Falcondo Ni-laterite deposits, central Dominican Republic, are reported. Samples of Ni-sepiolitefalcondoite vary in colour from whitish green to green depending on the NiO content (wt.%) and the amount of silica present. The texture is normally schistose and fria...

Resumen: El Yacimiento de Zeolitas de " Los Murcianos " , situado en la provincia de Almería cerca de la localidad de San José (Cabo de Gata), es el único yacimiento de zeolitas en explotación actualmente en España. Se emplaza en rocas volcánicas explosivas de tipo ignimbrita dacítica de la caldera de " Los Frailes ". La alteración hidrotermal de l...

Resumen Las zeolitas son minerales que poseen propiedades fisicoquímicas excepcionales debido a sus peculiares características químicas y estructurales. Los yacimientos más importantes se asocian a rocas volcánicas y se originan por transformación de cenizas volcánicas o por diagénesis de sedimentos que contengan componentes vulcanoclásticos. El ún...

High-resolution synchrotron X-ray diffraction recorded on a collection of palygorskites with different chemical compositions (obtained by analytical electron microscopy) permits unambiguous correlation of the crystallographic parameters a (or a sin  if a monoclinic phase is considered) with the nature of the octahedral sheet, i.e. with both the nu...

Cited By (since 1996): 12, Export Date: 11 October 2012, Source: Scopus, doi: 10.1130/2007.2423(13), Language of Original Document: English, Correspondence Address: Gutiérrez-Alonso, G.; Departamento de Geología, Facultad de Ciencias, Universidad de Salamanca, 37008 Salamanca, Spain; email: gabi@usal.es, References: Amthor, J.E., Grotzinger, J.P.,...

Palygorskite fibers growing along fault planes in the outcrops of a large fault zone in SE Spain (Carboneras Fault Zone: CFZ; Serrata de Níjar) were studied by X-ray diffraction, scanning electron microscopy-energy dispersive X-ray analysis, and transmission electron microscopy-analytical electron microscopy. The structural formulae, calculated per...

Wetlands are particularly sensitive environments receiving attention from the natural sciences community due to their wealth of both flora and fauna, and often considered as natural parks. In the Tablas de Daimiel (La Mancha, Central Spain), Digital Airborne Imaging Spectrometer data (DAIS 7915) have been analyzed to map geological processes on are...

Wetlands are particularly sensitive environments receiving attention from the natural sciences community due to their wealth of both flora and fauna, and often considered as natural parks. In the Tablas de Daimiel (La Mancha, Central Spain), Digital Airborne Imaging Spectrometer data (DAIS 7915) have been analyzed to map geological processes on are...

Maya blue is an organo-clay artificial pigment composed of indigo and palygorskite. It was invented and frequently used in Mesoamerica in ancient times (eighth to 16th centuries). We analyse in this paper one of the characteristics of Maya blue that has attracted the attention of scientists since its rediscovery in 1931: its high stability against...

The palygorskite of the Volcanic Complex near of Lisbom (Portugal) is particular both in the size of the fibres and in chemical composition. It appears as veins of very pure mineral. From hand specimen and optical observations it can be described as a macroscopic palygorskite. The crystals are large with exfoliation traces of several hundred micron...

The influence of chemical composition to position and intensity of the absorption bands observed in the FTIR spectra of palygorskite has been studied by a detailed comparative study of six samples. Palygorskites studied have high purity and different chemical composition. At one extreme, there are two samples that correspond to Mg-rich palygorskite...

The Allou Kagne (Senegal) deposit consists of different proportions of palygorskite and sepiolite, and these are associated with small quantities of quartz and X-ray amorphous silica as impurities. No pure palygorskite or sepiolite has been recognized by X-ray diffraction. Textural and microtextural features indicate that fibrous clay minerals of t...

A lo largo de su historia el hombre ha utilizado los mi nerales, entre otros muchos usos, en su alimentación. Las «tierras comestibles» han sido, por lo general, utilizadas para aportar al hombre complementos minerales, contra rrestar componentes perjudiciales en su dieta (como las fitotoxinas) y/o para ciertos tratamientos médicos. En animales la...

Hyperspectral imagery has been able to distinguish paleoflooded areas related to a receding wetland due to differential mineralogical contents associated with variable humidity available in the past, and palustrine and fluvial processes, through maps performed using hyperspectral image processing. Gypsum, carbonate and organic matter are paleoclima...

We present a study of the Mg K-edge on sepiolite and palygorskite performed at the INFM BEAR beamline at Elet-tra synchrotron light source (Trieste). These two clays, although having very similar structures, show some different features in their near-edge. Mg is in octahedral coordination with oxygens, hydroxyl groups or water, for both paly-gorski...

Gentle sloping terrains along the margins of fluvio lacustrine systems include morphological fea- tures related to landscape development under changing climate conditions, mainly during Quater- nary times. At the headwater catchment areas of large rivers, such sedimentary and morphological record systems reflect water availability changes giving va...

In the La Codosera syncline diabase sills with unusual size in the Spanish territory (kilometric lenght and hectometric width) are interleaved with supra-Ordovician metasediments. The large size of these bodies and their blackish colour are positive factors, thinking about their exploitation as ornamental rock. A systematic study of the potentialit...

In the La Codosera syncline diabase sills with unusual size in the Spanish territory (kilometric lenght and hectometric width) are interleaved with supra-Ordovician metasediments. The large size of these bodies and their blackish colour are positive factors, thinking about their exploitation as ornamental rock. A systematic study of the potentialit...