La « Formation Cangalli » (Cordillère Orientale, Bolivie) est une formation détritique, glaciofluviatile au potentiel aurifère (paléo-placer) avéré dans la région de Tipuani-Mapiri. Cette thèse a pour objectif de déterminer l’origine, la source, les modalités d’apport ainsi que les conditions de dépôts de la « Formation Cangalli » sur un secteur en cours d’évaluation par la société Rexma SAS (secteur de la mine « La Esperanza », sud de Caranavi). L’analyse de la structure de la formation et de la répartition de l’or doit permettre d’évaluer le potentiel aurifère de ce secteur et de proposer des guides de prospection de l’or. Le travail a consisté à développer en parallèle des approches terrain (topographie, cartographie, exploration de ruisseaux, étude de faciès sédimentologiques, études granulométriques sur gros volume, échantillonnage) et laboratoire (caractérisation des clastes et de la matrice par pétrographie optique, MEB, DRX, microsonde, CHONS). L’analyse sédimentologique a permis de proposer un modèle de remplissage en adéquation avec l’évolution tectonique de la Cordillère Orientale des Andes. Le remplissage présente 4 séquences dont 3 d’entre elles possèdent une alternance entre des dépôts fluviatiles et des dépôts de cônes alluviaux.La comparaison des deux faciès de Cangalli aisément identifiables sur le terrain par deux couleurs différentes (bleu et rouge) a montré que la distinction n’était pas stratigraphique mais liée à une altération affectant la formation initiale bleue.L’étude de la distribution des particules d’or (125-1000 μm) a montré que l’or est d’origine hydrothermale. De plus, les résultats montrent clairement que la distribution de l’or est hétérogène dans la « Formation Cangalli » les niveaux les plus enrichis se trouvant en base de séquence. Ces résultats permettent de poser les bases d’une exploitation industrielle de la concession minière. / The “Cangalli Formation” (Eastern Cordillera, Bolivia) is a detrital, glacofluvial formation with an established gold potential (paleo-placer) in the Tipuani-Mapiri region. This thesis aims to determine the origin, source, contribution and deposition conditions of the "Cangalli Formation" on an area being assessed by the Rexma SAS Company (area of the mine “La Esperanza”, south of Caranavi). The analysis of the formation structure and gold distribution should allow to evaluate the gold potential of this sector and to provide guidelines for gold prospecting. Two parallel approaches have been developed: fieldwork (topography, mapping, stream exploration, sedimentological study of facies, granulometry, sampling) and laboratory experiments (clasts and matrix characterization using optical petrography, SEM, XRD, microprobe, CHONS). Sedimentological analysis allowed to propose a filling model in line with the tectonic evolution of the Andean Cordillera Real. The filling shows 4 sequences, 3 of them consist of an alternation between fluvial and alluvial deposits. Comparison of the two Cangalli facies easily recognizable on the field by two different colors (blue and red) showed that the distinction was not stratigraphic but associated with an alteration affecting the initial blue formation. The study of the distribution of gold particles (125-1000 microns) showed that gold is of hydrothermal origin. In addition, the results clearly show that the gold distribution is heterogeneous in the "Cangalli Formation" the riches levels being in the basal sequences. These results lay the groundwork for industrial exploitation of the mining concession.

No description available.

The Old Hickory is the largest of a series of Pliocene (?) age heavy mineral sand deposits in Virginia and North Carolina. The high density of heavy minerals allows for selective concentration during transport and deposition. Under the right conditions, placers of considerable size can be formed. The elliptically shaped ore body of the Old Hickory Deposit extends in a North - South direction and is approximately 13 km (8 miles) long and up to 2.5 km (1.5 miles) wide, with an average thickness of 6.5 m (20 feet). The deposit lies along the Fall Zone, where a thin wedge of Cenozoic Coastal Plain sediments unconformably overlies the older rocks of the Piedmont. The principal minerals of economic interest found in the heavy mineral sands at the site are ilmenite (FeTiO₃), leucoxene (Fe<SUB>2-x</SUB>Ti<SUB>3+x</SUB>O<SUB>9+x/2</SUB>) where x is less than or equal to 2, rutile (TiO₂), and zircon (ZrSiO₄). An important focus of this study is the alteration of ilmenite by leaching away of iron, which results in enrichment in titanium. Titanium metal is highly valued for its light weight and high strength. In terms of total economic value, however, the use of titanium dioxide pigments for paint, coated paper, and other products is far more important. As the value of the ore is heavily dependent on the titanium content, the weathering process is a matter of considerable interest to the mineral industry. Analysis of ilmenite grains using reflected light microscopy revealed a wide range of alteration textures. Quantitative analysis and mapping of trace elements showed altered areas with enrichment in Ti and depletion in Fe, Mn, Mg, and Cr. It is believed that the weathering process took place in a reducing environment prior to final deposition according to the reaction: Fe²⁺TiO₃ + 2H⁺ --> Fe²⁺ (aq) + TiO₂ + H₂O Reducing environments are found in water-logged soils such as floodplains and other low-lying areas. Repeated cycles of burial and exhumation during transport would have created conditions ideal for the removal of iron from the ilmenite. / Master of Science

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1940. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed March 8, 2010)

Thesis (M. Sc.)--University of Alberta, 1997. / Submitted to the Faculty of Graduate Studies and Research in partial fulfilment of the requirements for the degree of Master of Science, Department of Earth and Atmospheric Sciences. Also available online.

En este artículo intento responder a la pregunta de si son –o al menos pueden ser– pluralistas las éticas de la vida buena. Por tales se entienden las éticas teleológicas, centradas en el fin último o bien supremo del individuo humano. ¿Pueden, pese a su aparente individualismo, ser éticas pluralistas? Para responder, me circunscribo al Filebo de Platón, en que el autor, superando las visiones que identifican el bien humano con la vida de placer o con la vida del conocimiento, lo identifica con una vida mixta, que es una mezcla de las dos. Desarrolla, pues, a mi modo de ver, una ética estructuralmente pluralista: (1) por la actitud, eminentemente dialógica, de sus interlocutores; (2) por el método de la división que emplea, el cual va de la pluralidad indefinida a la unidad, y de esta a una pluralidad definida; (3) por el principio ontológico de lo Uno-Múltiple en que se funda; (4) por el contenido que asigna al bien de la existencia humana. Sobre todo por este contenido –esencialmente inclusivo– la ética del Filebo ha ejercido una influencia decisiva en la filosofía moral igualmente pluralista de la Ética a Nicómaco.

The Vaal Reef placer is situated on the unconformable junction of the Strathmore and Stilfontein formations of the Johannesburg Subgroup. Within the South Division of the Vaal Reefs Exploration and Mining company lease, the Vaal Reef Placer is shown to be composed of several different units. Each unit exhibits its own specific characteristics and trend direction which can be used to establish distinct "Reef packages". These packages can be mapped in such a way as to provide a preliminary lithofacies map for the Vaal Reef Placer. The delineation of such geologically homogenous zones, and the development of a suitable depositional model, can be utilised in several ways. The characteristics of a particular zone are shown to influence the control of stoping width, evaluation of remnant pillars and the geostatistical methodology of evaluating current and future ore reserve blocks.

No description available.

Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1936. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed June 9, 2010) Includes bibliographical references (p. 93).

En la lectura de la Ética a Nicómaco se evidencia un tópico recurrente: el placer. En la presente, se examina la naturaleza del placer y su relación con la felicidad en dicha obra. Luego, la reflexión ética se complementa con una reflexión psicológica sobre un principio cuyo objeto es el placer: el principio pollyanna. Después, se muestra la insuficiencia de los dos argumentos utilizados por Aristóteles para refutar que el placer sea el bien supremo. Entonces, se presenta el argumento de la Máquina del Placer para refutar dicha tesis. Finalmente, se expone uno de los límites del placer: el sentido. / Tesis