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Journal articles on the topic 'Llallagua'

Author: Grafiati

Published: 4 June 2021

Last updated: 12 February 2022

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1

Rodgers, K. A., H. W. Kobe, and C. W. Childs. "Characterization of vivianite from Catavi, Llallagua Bolivia." Mineralogy and Petrology 47, no. 2-4 (1992): 193–208. http://dx.doi.org/10.1007/bf01161567.

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2

Raade, G., J. D. Grice, and R. Rowe. "Ferrivauxite, a new phosphate mineral from Llallagua, Bolivia." Mineralogical Magazine 80, no. 2 (April 2016): 311–24. http://dx.doi.org/10.1180/minmag.2015.079.7.15.

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AbstractFerrivauxite, ideally Fe3+Al2(PO4)2(OH)3·5H2O, is an oxidized equivalent of vauxite, Fe2+Al2(PO4)2(OH)2·6H2O, and forms oxidation pseudomorphs after that mineral. It occurs in association with sigloite and crandallite at the Llallagua tin deposit, Bolivia. It is triclinic, space group P1̄, with a = 9.198(2), b = 11.607(3), c = 6.112(2) Å, α = 98.237(9), β = 91.900(13), γ = 108.658(9)°, V = 609.7(5) Å3, Z = 2. Strongest reflections of the powder X-ray diffraction pattern are [dobsin Å(Iobs)(hkl)]: 10.834(100)(010), 8.682(24)(100), 8.242 (65)(110), 6.018(28)(001), 5.918(23)(1̄10), 5.491 (30)(1̄20), 4.338(26)(200), 2.898 (32)(300). The structure was refined to R1 = 0.0369 for 3244 observed reflections. Twinning occurs on {010}. Ferrivauxite is isotypic with vauxite but with positional disorder of the Fe1 site and some of the oxygen sites. Disorder is also indicated by the infrared spectrum. One of the water molecules in vauxite is deprotonated in conjunction with the oxidation process and becomes a hydroxyl group. Ferrivauxite is translucent to transparent, has a golden brown colour with a pale yellow-brown streak and vitreous lustre. It is brittle with an irregular fracture and shows no cleavage. The Mohs hardness is estimated to be ∼3½ by comparison with vauxite. D(calc.) is 2.39 g cm–3for the empirical formula Fe3+0.94Mn0.01Al1.98P2.05O8(OH)3· 5H2O, obtained by electron-microprobe analysis in wavelength dispersive spectroscopy mode. The mineral is optically biaxial negative with α = 1.589(1), β = 1.593(1), γ = 1.596(1); the refractive indices are higher than those of vauxite.

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3

Vásquez-Machado, Andrés, and Dora Guarachi-Catari. "Epidemiología del intento suicida en el Hospital Madre Obrera, Llallagua, Bolivia." Revista de Neuro-Psiquiatria 73, no. 2 (February 22, 2013): 39–44. http://dx.doi.org/10.20453/rnp.v73i2.1656.

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Objetivo: Estudiar las características epidemiológicas de las personas que asistieron por intento suicida a un hospitalde Potosí, Bolivia. Material y métodos: Se realizó un estudio con 56 personas que acudieron al Hospital MadreObrera de Llallagua (Potosí, Bolivia) que tuvieron un intento suicida entre el 6 de junio de 2006 y el 31 de octubrede 2007. Mediante entrevistas individuales se determinaron las variables demográficas, métodos y motivos delintento suicida, antecedentes personales y familiares de conducta suicida, diagnóstico psiquiátrico y factores inherentesa la tentativa actual. Resultados: La razón mujeres/varones fue 2:1. El grupo de edad más afectado fue el de 15 a 24años (55,4%). Entre los hombres, predominaron los solteros (72,2%) y los estudiantes (50%); y entre las mujeres,las que tenían pareja (50%) y las amas de casa (42,1%). El método suicida más utilizado fue la ingestión deorganofosforados (67,8%), en tanto que los motivos más frecuentes fueron los conflictos con la pareja (42,6%) ycon la familia (37%). En 25% de la muestra persistía la ideación suicida; 21,4% tenía familiares con conductasuicida y 16,1% había realizado tentativas anteriores. El 83,9% realizó el intento suicida de manera impulsiva y51,8% estaba bajo los efectos del alcohol. Los diagnósticos psiquiátricos más frecuentes fueron los trastornos de lapersonalidad y la depresión. Conclusiones: Quienes intentan suicidarse son jóvenes, mujeres, estudiantes, amas decasa, hombres solteros y mujeres con pareja. La conducta suicida personal y en familiares, la ingestión de bebidasalcohólicas, así como tener un trastorno de personalidad son características frecuentes.(Rev Neuropsiquiatr2010;73:39-44).

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4

Rakovan, John, Matthew Newville, and Steve Sutton. "Evidence of heterovalent europium in zoned Llallagua apatite using wavelength dispersive XANES." American Mineralogist 86, no. 5-6 (May 2001): 697–700. http://dx.doi.org/10.2138/am-2001-5-610.

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5

Scholz, Ricardo, Ray L. Frost, Laura Frota, Fernanda Maria Belotti, and Andrés López. "SEM, EDX and vibrational spectroscopy of the phosphate mineral vauxite from Llallagua, Bolívia." Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 151 (December 2015): 149–55. http://dx.doi.org/10.1016/j.saa.2015.06.062.

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6

Ventruti, Gennaro, Emanuela Schingaro, Alessandro Monno, Maria Lacalamita, Giancarlo Della Ventura, Fabio Bellatreccia, Corrado Cuocci, Manuela Rossi, and Francesco Capitelli. "Structure Refinement and Vibrational Spectroscopy of Vauxite From the Type Locality, Llallagua (Bolivia)." Canadian Mineralogist 54, no. 1 (January 2016): 163–76. http://dx.doi.org/10.3749/canmin.1500060.

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7

Welch, Mark D., and Anthony R. Kampf. "Stoichiometric partially-protonated states in hydroxide perovskites: the jeanbandyite enigma revisited." Mineralogical Magazine 81, no. 2 (April 2017): 297–303. http://dx.doi.org/10.1180/minmag.2016.080.099.

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AbstractThe original description of the hydroxide perovskite jeanbandyite gives a formula (Fe1–x3+,□x)(Sn1–y,□y) (OH)6 (□= vacancy), which implies the possibility of stoichiometric vacancies at B and B' sites. The validity of this formula has been questioned subsequently. Furthermore, jeanbandyite has metrically a cubic unit cell, but it is optically uniaxial. It is clear that a structure determination is needed to clarify the nature of this enigmatic mineral. Previous studies could find no crystals of sufficient quality for structure determination using X-ray diffractometers available at the time. Crystals of jeanbandyite from Hingston Down, Cornwall, UK and the type locality Llallagua, Bolivia, have been found that are of a quality that allows structure refinement by single-crystal X-ray diffraction. Structural data for crystals from each locality are presented that clarify the nature of jeanbandyite and raise some interesting questions concerning the significance of partially deprotonated states in perovskite-type structures. The structures of both jeanbandyite crystals are cubic with space group Pn3 and unit-cell parameters a = 7.658(2) Å (Llallagua) and 7.6427(2) Å (Hingston). The octahedral tilt system is a+a+a+ and corresponds to that of the aristotype of BB'(OH)6 hydroxide double perovskites. Structure determination demonstrates that B is very Fe3+-rich and B' is filled by Sn, thereby requiring revision of the general jeanbandyite formula to Fex3+Fe(1–x)2+Sn(OH)(6–x)Oxfor 1≥ × > 0.5, with an ideal end-member formula Fe3+Sn(OH)5O. As such, jeanbandyite corresponds to oxidized natanite with partially deprotonated oxygen sites. This stoichiometry cannot be represented in space group Pn3̄ for the observed unit cell as it implies more than one non-equivalent oxygen atom. Consequently, it is inferred that there is no long-range ordering of deprotonated oxygen sites. It is, however, conceivable that the uniaxial optical character of jeanbandyite is linked to the local short-range order of deprotonated domains.

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8

Romero, Francisco Martín, Carles Canet, Pura Alfonso, Rubén N. Zambrana, and Nayelli Soto. "The role of cassiterite controlling arsenic mobility in an abandoned stanniferous tailings impoundment at Llallagua, Bolivia." Science of The Total Environment 481 (May 2014): 100–107. http://dx.doi.org/10.1016/j.scitotenv.2014.02.002.

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9

Zola, Fidel Pillco, and Flores Mamani Juvenal. "Estudio de la erosión hídrica laminar de la tioc del ayllu sikuya del municipio de Llallagua." Revista Ibero-Americana de Ciências Ambientais 7, no. 1 (January 9, 2016): 76–81. http://dx.doi.org/10.6008/spc2179-6858.2016.001.0006.

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Las Tierras Indígena-Originaria Campesinas (TIOC) del ayllu Sikuya del municipio de Llallagua, del departamento de Potosí, Bolivia, que alcanza a una superficie de 126,83 km2,están emplazadas en medio de una configuración fisiográfica montañosa y, probablemente, como efecto de esta situación sufren una fuerte erosión. De ahí, fue necesario realizar un estudio sobre la determinación de la erosión hídrica laminar, aplicando el modelo de la ecuación universal de pérdida de suelo (USLE), cuyos factores son: erosividad (R), erodabilidad (K), longitud de la pendiente (LS), cobertura vegetal (C) y prácticas de conservación de suelos (P). Como herramienta de obtención del mapa de pérdida de suelo por erosión hídrica laminar se utilizó las técnicas del Sistema de Información Geográfica (SIG). De los resultados obtenidos, se colige que, del total de la superficie de la TIOC: 43,12 km2 (34 %) tiene una pérdida de suelo menor a 7,41 tn/ha/año, de grado ligero; sin embargo, en cuestión de degradación ambiental ya preocupa que 83,71 km2 (66 %) tenga una pérdida de suelo mayor a 7,41 tn/ha/año, de grado moderado a muy severo.

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10

Betkowski, Wladyslaw B., John Rakovan, and Daniel E. Harlov. "Geochemical and textural characterization of phosphate accessory phases in the vein assemblage and metasomatically altered Llallagua tin porphyry." Mineralogy and Petrology 111, no. 4 (March 31, 2017): 547–68. http://dx.doi.org/10.1007/s00710-017-0510-6.

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11

Kempe, U., B. Lehmann, D. Wolf, N. Rodionov, K. Bombach, U. Schwengfelder, and A. Dietrich. "U–Pb SHRIMP geochronology of Th-poor, hydrothermal monazite: An example from the Llallagua tin-porphyry deposit, Bolivia." Geochimica et Cosmochimica Acta 72, no. 17 (September 2008): 4352–66. http://dx.doi.org/10.1016/j.gca.2008.05.059.

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12

Rakovan, John, Diane K. McDaniel, and Richard J. Reeder. "Use of surface-controlled REE sectoral zoning in apatite from Llallagua, Bolivia, to determine a single-crystal SmNd age." Earth and Planetary Science Letters 146, no. 1-2 (January 1997): 329–36. http://dx.doi.org/10.1016/s0012-821x(96)00226-9.

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13

Della Ventura, Giancarlo, Francesco Capitelli, Giancarlo Capitani, Gennaro Ventruti, and Alessandro Monno. "X-ray Structure Refinement and Vibrational Spectroscopy of Metavauxite FeAl2(PO4)2(OH)2·8H2O." Crystals 9, no. 6 (June 6, 2019): 297. http://dx.doi.org/10.3390/cryst9060297.

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In this paper, we provide a crystal-chemical investigation of metavauxite, ideally FeAl2(PO4)2(OH)2·8H2O, from Llallagua (Bolivia) by using a multi-methodological approach based on EDS microchemical analysis, single crystal X-ray diffraction, and Raman and Fourier transform infrared (FTIR) spectroscopy. Our new diffraction results allowed us to locate all hydrogen atoms from the structure refinements in the monoclinic P21/c space group. Metavauxite structure displays a complex framework consisting of a stacking of [Al(PO4)3(OH)(H2O)2]7− layers linked to isolated [Fe(H2O)6]2+ cationic octahedral complex solely by hydrogen bonding. The hydrogen-bonding scheme was inferred from bond-valence calculations and donor-acceptor distances. Accordingly, strong hydrogen bonds, due to four coordinated H2O molecules, bridge the [Fe(H2O)6]2+ units to the Al/P octahedral/tetrahedral layer. The hydroxyl group, coordinated by two Al atoms, contributes to the intra-layer linkage. FTIR and Raman spectra in the high-frequency region (3700–3200 cm−1) are very similar, and show a complex broad band consisting of several overlapping components due to the H2O molecules connecting the isolated Fe(H2O)6 and the adjacent Al/P octahedral/tetrahedral layers. A sharp peak at 3540 cm−1 is assigned to the stretching mode of the OH group. The patterns collected in the low-frequency region are dominated by the stretching and bending modes of the PO43− group and the metal-oxygen polyhedra.

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14

Gatta, G. D., P. Vignola, and M. Meven. "On the complex H-bonding network in paravauxite, Fe2+Al2(PO4)2(OH)2·8H2O: A single-crystal neutron diffraction study." Mineralogical Magazine 78, no. 4 (August 2014): 841–50. http://dx.doi.org/10.1180/minmag.2014.078.4.05.

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AbstractThe crystal structure and the chemical composition of a paravauxite from the Siglo Veinte Mine, Llallagua, Bustillo Province, Potosi Department, Bolivia [Fe(Fe0.9162+Mn0.0162+Mg0.064Ca0.002)∑0.998Al(1)Al(2)Al2.005P(P1.998Si0.002)∑2O8(OH)2·8H2O, a = 5.242(1) Å, b = 10.569(2) Å, c = 6.970(2) Å, α = 106.78(3)°, β = 110.81(2)° and γ = 72.29(2)°, space group P], was investigated by single-crystal neutron diffraction and electron microprobe analysis in wavelength-dispersive mode. Neutron-intensity data were collected at 293 K and anisotropic structure refinement was performed. At the end of the refinement no peak larger than ±1.3 fm/Å3 was present in the final difference-Fourier map of the nuclear density. The final statistical index was R1 = 0.0495 for 194 refined parameters and 1678 unique reflections with Fo > 4σ(Fo). Eleven independent H sites (i.e. H(1), H(2), H(3), H(4A), H(4B), H(5), H(6), H(7), H(8), H(9A) and H(9B)), all at ∼1 Å from the respective O sites, were located successfully. H(4A) and H(4B) and H(9A) and H(9B) are two mutually exclusive subsite couples only 0.4−0.6 Å apart. The complex H-bonding scheme in the paravauxite structure is now well defined and 12 independent H bonds, with an energetically favourable bonding configuration, are described. A comparison between the previous experimental findings based on Raman and infrared spectroscopy and those obtained in this present study is carried out. Paravauxite provides the rare opportunity to investigate the H-bond configuration of coexisting hydroxyl groups and H2O molecules in minerals by single-crystal neutron diffraction. H2O is present as zeolitic (i.e. lying in the cavities) and non-zeolitic H2O (i.e. bonded to Al or Fe to form Al or Fe octahedra).

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15

"Speculations Linking Monazite Compositions to Origin: Llallagua Tin Ore Deposit (Bolivia)." Resources 6, no. 3 (July 29, 2017): 36. http://dx.doi.org/10.3390/resources6030036.

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