Este trabalho, complementado por documentação geológica da região do depósito e por uma revisão não só dos métodos clássicos de avaliação de reservas como também dos conceitos e técnicas de amostragem na pesquisa mineral, apresenta os resultados de um estudo comparativo de amostragem em furos de sondagem e em galerias para pesquisa de cassiterita no Pegmatito Xupé, em Monte Alegre de Goiás, GO. Os corpos pegmatíticos, por exibirem grande variabilidade natural dificultam os processos de amostragem e pesquisa, que, não obstante isso, são de vital importância, quando se pensa no aproveitamento industrial dessa fonte de vários metais raros. Os estudos mostram existir grande diferença de teores médios de estanho nos furos de sondagem e em galeria: basta, para isso, observar a redução constante da variância em face da relação fundamental da amostragem: volume x variância. Para corpos pegmatíticos constatou-se que a amostragem de grande massa é a mais indicada, e os resultados analíticos de furos de sondagem devem ser vistos apenas como valores indicativos, mas importantes, numa rápida visualização tridimensional do corpo mineral. Com os dados levantados no inventário da pesquisa mineral, a avaliação de reservas do Pegmatito Xupé, pelo método dos perfis padrão, é da ordem de 415000 m³ de minério com 1695 g de Sn/m³ e 53 g de \'Ta IND. 2\'\'O IND. 5\'/m³. / This paper presents the results of a comparative statistic study between drill hole sampling and drift\'s channel sampling results carried out during the underground exploration and ore reserve evaluation in the Xupé pegmatite - Monte Alegre de Goiás - State of Goiás. The complete geological documentation available in the area, a revision of classical methods for ore reserve estimation and a revision of concepts and techniques of sampling are also presented in this dissertation. The pegmatite ore bodies usually exhibit a large natural grade variability. In this way the sampling procedures are not easy to acomplish being of capital importance for the appropriate evaluation and industrial use as a source of rare metals. When both drill hole and drift Sn grade results are compared, large differences of the average grade are noticed. This is true because of the inverse correlation between variance and sample volume which keeps the fundamental relation of sampling: volume x variance = constant. It is concluded that bulk sampling is most indicated for Sn pegmatite ore bodies evaluation and the grade values obtnined from drill cores should be used to delineate the tridimensional geometry and ore limits. Measured and indicated reserves are of the order of 415000 m³, with 1695 g Sn/m³ and 53 g \'Ta IND. 2\'\'O IND. 5\'/m³.

Graduation date: 1967

A method of quantifying the susceptibility of upland catchments to acidification, utilizing the influence of atmospheric sea-salt deposition in maritime dominated climates, is evaluated. Inputs of marine-derived Sodium (Na) provide a scale against which to measure inputs of alternative base cations, principally Ca and Mg, which are released through weathering reactions. Hence, the use of a Na base cation dominance index, as a means of quantifying catchment weathering rates, is proposed. Mineral weathering is important as it provides the only long-term sink for acid inputs including those of anthropogenic pollution. The Critical Loads approach provides a scientific tool with which to address appropriate levels of pollution control legislation by deriving acceptable levels of pollution below which sensitive components of various ecosystems will not be damaged. Critical loads for soils and freshwaters currently rely on methods to determine crucial base weathering rates and associated alkalinity generation. Existing methods are complicated and data intensive and have attracted a level of criticism from scientists in this field. The calibration of the index for streamwaters against both catchment weathering rates and alkalinity production is described across a major river system in Northeast Scotland. Clear differences are demonstrated between relative base cation proportions in streamwaters, soil solutions and on soil exchange sites. Atmospheric base cation inputs are generally shown to exceed those from internal weathering sources. The %Na dominance approach is proposed as being a cost-effective, field-based determination method capable of achieving a greater degree of reliability in the determination of weathering rates. This research has shown that the index has the benefit of providing a unifying approach between catchment soils and surface waters, which is currently lacking in critical loads methodology. The index has potential to describe both spatial and temporal variations in catchment weathering at a range of scales.

Thesis (M.Com.(Taxation))--University of Pretoria, 2009. / Summary in English and Afrikaans. Includes bibliographical references.

Thesis--Belgrad. / At head of title: Univerzitet u Beogradu. Summary also in English. Bibliography: p. 205-208.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Uppsala universitet, 1781, Thesis (doctoral). / Goldsmiths'-Kress no. 12138.0. - OCLC, 24258510. - Reproduction of original from Kress Library of Business and Economics, Harvard University.

Thesis (M.L.)--University of California, Berkeley, 1909. / Includes bibliographical references (preface).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1984. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 361-397).

Thesis (doctoral)--Uppsala universitet, 1781. / Reproduction of original from Kress Library of Business and Economics, Harvard University. Goldsmiths'-Kress no. 12138.0.