Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. F. E. Riede determined to be Frederick Edward Riede and E. F. Boland determined to be Earl Frederick Boland from "Forty-First Annual Catalogue. School of Mines and Metallurgy, University of Missouri". F. E. Riede received a Bachelor of Science degree in Metallurgical Engineering and E. F. Boland received a Bachelor of Science degree in Mining Engineering. Both degrees determined from "1874-1999 MSM-UMR Alumni Directory". Title from title screen of thesis/dissertation PDF file (viewed February 27, 2009)

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1907. / The entire thesis text is included in file. Typescript. Illustrated by author. E. E. Jones determined to be Elston Everett Jones from "Forty-First Annual Catalogue. School of Mines and Metallurgy, University of Missouri". Title from title screen of thesis/dissertation PDF file (viewed February 27, 2009)

Turbidite-hosted gold deposits contribute a significant proportion to world lode gold production and have also provided substantial gold to alluvial resources. Turbidity current deposits occur throughout geological time within Archaean greenstone belts, Proterozoic orogenic belts and rifted passive continental margins, and Palaeozoic geosynclines. Representing the end member of the sedimentary cycle, turbidites have the attribute of preservation not only on an individual bed basis but also due to below wave base accumulation in submarine deeps. Cyclic deposition according to the Bouma sequence punctuates turbidite deposition by a series of diastems. Accumulation of organic, pelagic and chemical sediments may concentrate gold to protore enrichment levels i n a primary sedimentary environment. Dewatering during diagenesis and low-grade metamorphism under reducing conditions may redistribute gold with transport as low energy organo- and thio-complexes. Gold may precipitate with diagenetic pyrite and silica near black shale and/or partially replace fine carbonate detritus. Gold solubility increases with high grade amphibolite facies metamorphism (T 400ºC) when efficient leaching of gold and transport by simple chloro- and hydroxychloro - complexes to lower greenschist regions takes place. Reduced permeability of turbidite strata induces hydrofracturing which focuses dewatering solutions. Gold is deposited due to pressure and temperature decrease or local changes in physico - chemico conditions caused by the reaction of fluids with wall rocks (reactive beds in turbidites are predominantly carbonaceous strata). The largest of turbidite - hosted goldfields are confined to back -arc or marginal sea basins with restricted oceanic circulation. The richest concentrations of gold occur proximal to the original source within the greenschist facies formations lowermost in a thick turbidite sequence and exhibit strong combined structural and lithological association. Turbidites represent important strata for the concentration and preservation of gold not only during sedimentation and diagenesis but also during later deformation and metamorphism.

Sediment-hosted disseminated gold deposits in Nevada, western United States are major gold sources and contain reserves in excess of 1 500 metric tons of gold (Percival et aI., 1988). Discovery of these deposit types continues at a pace, with Placer Dome announcing a mojor discovery, Pipeline, to the south of the Gold Acres Mine, along the Battle Mountain - Eureka Trend in 1994 (The Northern Miner, 1994). Host sediments favoured for disseminated gold mineralisation are thinly bedded silty limestones , carbonate debris flows and to a lesser extent shale, chert and sandstone. The distribution of mineralisation is controlled essentially by the intersection of high-angle faults, which acted as conduits for hydrothermal fluids, with favourable host lithologies, anticlines, low-angle faults and other high-angle faults. Geochemical signature for these deposits is simple being Au, Ag, As, Sb, Hg, Tl, Te, F and Ba, but individual element concentrations vary greatly between and within deposits. Age of mineralisation is cause for considerable debate, and ages ranging between isotopic dates of approximately 117 Ma to early to mid-Tertiary (30-40 Ma) are proposed. Most of these deposits are situated along three major trends namely the Carlin, Battle Mountain - Eureka and Getchell trends. The Battle Mountain - Eureka trend and, to a lesser extent the Carlin trend, are defined by major linear aeromagnetic and gravity anomalies , which are believed to reflect deep-seated structures. Most deposits are hosted in autochthonous Devonian, thinly bedded, silty limestones that occur as windows through what is believed to be allochthonous Ordovician siliciclastic sediments, which were transported from west to east along the Roberts Mountains thrust during the late-Devonian Antler Orogeny. However, recent fossil dating of what were thought to be Ordivician siliciclastic sediments, gives a Devonian age. This questions the age of Ordivician sediments at the other deposits and the interpretation of the structural windows in which deposits are located. Fault-bounded, proximal, carbonate debris-flow breccias are now recognised as a major host to mineralisation. These debris flow breccias, together with interbedded carbonate and siliciclastic sediments, carbonaceous sediments and soft sediment deformation are all characteristics of lithologies in pull-apart basins which develop along a major strike slip faults. It is proposed that sediment-hosted disseminated gold mineralisation is controlled by the distribution of deep-seated long-lived, predominantly right-lateral strike-slip faults. It is along these strike-slip faults that syn-sedimentary pull-apart basins developed, within which sediments favoured by epigenetic gold mineralisation were deposited. These pull-apart basins were then overprinted by post-depositional extensional structures, such as negative flower structures. Igneous intrusions and hydrothermal cells have exploited these extensional structures in both compressional and extensional regional tectonic regimes. This model explains the characteristics of the host sediment at many of the deposits, the spatial relationship between igneous intrusion and mineralisation, spanning the period Cretaceous through to mid-Tertiary, the distribution of deposits as districts along major regional trends and why hydrothermal activity is noted between deposit districts but with no complementary mineralisation. Mineralisation is controlled predominantly by high angle structures and although the recent age for mineralisation at the Betze/Post deposit is ~ 117 Ma (Arehart et aI., 1993a), placing it in the compressional Sevier Orogeny, these high-angle structures would be developed within local extensional tectonic domains as described above. This model can, and should, be applied to other areas of the world where similar geological features exist. In exploring for these deposits in Nevada the distribution of Ordovician siliciclastic sediments should be reviewed, especially where spatially associated with deep regional structures. Ordovician sediments have historically been regarded as unfavourable, hence large areas for potential exploration have been ignored but with new ages for these sediments this opens large areas for potential discoveries. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

This thesis focuses on platinu'm group element (PGE) mineralization in the Unki Section of the Selukwe Subchamber of the Great Dyke (Zimbabwe), and is based on drill hole intersections and underground and surface exposures of the Main Sulphide Zone (MSZ) which hosts significant concentrations of PGE. The petrological and geochemical data presented are part of a broader study currently underway and the present are restricted to the 2m section of the PGE-rich MSZ encountered in drill hole MR126. The PGE-rich MSZ at Unki is unique in having a shear, locally referred to as the Footwall Shear, developed at or close to its base . It is however, similar to the other PGE occurrences on the Great Dyke (MSZ) in having its hanging-wall restricted to within 1m of the websterite/bronzitite contact. Slight axial tilting to t he west is indicated by steeper dips on the eastern flank. The sulphide concentration wit hin the MSZ can be used as a rough guide to the PGE-rich zone, but is not sufficiently precise to be used in stope control. The visual identification of the potentially mineable zone remains a problem that is unlikely to be solved. Based on petrological evidence, the bulk of the sulphides with which the PGE are associated, are cumulus in status. This provides unequivocal evidence for an orthomagmatic origin of the MSZ. The dominant platinum group mineral (PGM) phase is the Arsenide/Sperrylite group which is most commonly found at the contact zones between base metal sulphides (BMS) and gangue. The PGM range up to 90 ~m in length. Geochemical evidence from the analyses of cumulate orthopyroxenes through the 2m PGE-rich MSZ interval at Unki reveals a trend of arked Fe enrichment upwards which corresponds to an enrichment in sulphide. This indicates that precipitation of sulphide was caused by fractionation with lowering of temperature in the magma. The Fe enrichment is followed by a reversal in Mg# of orthopyroxene which corresponds to the decrease in sulphide content, suggest i ng that the termination of the PGE-rich MSZ was due to an increase in temperature associated with an influx of new magma. Coupled with these magmatic events are a complex interplay of chemical and physical processes occurring at a critical stage in the overall fractionation of the Great Dyke magma chamber. The overall persistence and continuity of t he PGE zone as observed in the Unki area is consistent with the inferred orthomagmatic origin of the mineralization

Most of the Great Basin sediment-hosted gold deposits are located along well defined, northwest-striking trends. Trends coincide with faults, intrusive rocks and magnetic anomalies. Sedimentary host rocks are siltstone, sandstone, conglomerate, argillic, interbedded chert and shales. Silty bedded silty dolomites, limestone and carbonaceous shales are the most favourable hosts. High, and locally, low-angle faults are very important structural features related to the formation of the ore bodies. High-angle faults are conduits of hydrothermal fluids which react, shatter and prepare the favourable host rock. Decalcification, silicification, and argillization are the most common hydrothermal alteration types. Jasperoid (intense silica replacement) is a significant characteristic; not all of these deposits are gold-bearing. Most deposits contain both oxidized and unoxidized ore. Fine grained disseminated pyrite, arsenian pyrite, and carbonaceous material are the most common hosts for gold in many deposits. These deposits are also characterized by high Au/Ag ratios, notable absence of base metal and geochemical associations of Au, As, Sb, Hg, Ba and TI. Recently numerous sediment-hosted gold deposits have been recognized in different regions of the world. They vary in their size, grades, textwe, host rock lithology, degrees of structural control and chemical characteristics. However, they have many common features which are very similar to the general characteristics of sediment-hosted gold deposits in the Great Basin, U.S.A. Besides these similarities, several unusual features are recorded in some newly discovered deposits elsewhere, such as predominant fault controlled paleokarst related mineralization and the lack of two very common trace elements (Hg, TI) in Lobongan/Alason, Indonesia; and Early Proterozoic age metamorphosed host rocks and lack of Sb in Maoling, China. The discovery of the deep ores in the Post-Betze and Rabbit Canyon, Nevada, proposed sediment-hosted Au emplacement at deeper level (4 ± 2 km; Kuehn & Rose, 1995) combined with a lack of field evidence for paleowater table and paleosurface features has ruled out a shallow epithermal origin. Recent discoveries in other parts of the world throw important new light on the ongoing genetic problems. Intrusive rocks are present in nearly all sediment-hosted gold deposits. Numerous intrusion-centred districts worldwide are characterized by tWo or more different mineralization types and consequently by metal zoning. Sediment-hosted gold deposits are proposed as a distal part of intrusion-centred magmatic hydrothermal systems (Sillitoe &Bonham, 1990).

[No abstract available] / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate

The extraction of nickel and cobalt, from nickeliferous laterite, together with the hydrothermal precipitation of hematite has been investigated. In order to emphasize the relevance and significance of this process, an appraisal is made of the state of the nickel, cobalt and iron industries. A compilation of the annual production of the respective ores on the world market is included with an examination of the future uses and demand of nickel and cobalt. Solubility relationships for iron (III) compounds in aqueous solution are reviewed in terms of pH, solution composition and temperature. The thermodynamic data used at elevated temperatures between 60°C (333°K) and 200°C (473°K) have been estimated by using the "Entropy correspondence principle" method of Criss and Coble. A sample calculation is shown in Appendix A. The effects of (a) temperature; (b) ferric chloride concentration, (c) hydrochloric acid concentration and (d) pulp density were studied in order to evaluate extraction conditions. Generally, metal extraction increased with temperature and ferric chloride concentration. At 423°K, over 90 percent of the nickel was extracted with a ferric chloride concentration greater than 1M. Since appreciable amounts of gangue dissolved under most conditions, thereby consuming acid, a discussion on the recovery of hydrochloric acid is presented. Filtration of the precipitated hematite has proved difficult, because of the very fine nature of the particles. An overview of the nucleation and growth of particles in supersaturated solutions has therefore been included. This phenomenon is used to describe the phase changes which occurred during leaching experiments, and to propose an approach by which coarser particles might be achieved. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

Experiments were conducted to study the rate of oxidation of pyrite under conditions of varying pH, temperature and oxygen concentration. The rate of oxidation appears to be slightly increased below pH 3.00. In the basic range the oxidation is retarded as pH 9.00 is approached. Increases in temperatures cause increases in the rate of oxidation of pyrites. Corresponding decreases in the pH values are also noted. The rate of oxidation is increased by increaseing the concentration of oxygen. From these results, the possible use of pyrite in alkaline soils in the prevention of chlorosis caused by iron deficiency seems feasible.

This work represents the study of the biological oxidation of iron pyrite, FeS_2. The chief objective of the study was to investigate the possibility of biological oxidation of iron pyrite and to determine, if possible, the physical and chemical conditions under which the oxidative process occurs. The apparatus used to study the problem consisted of an air-lift percolator containing Ottawa sand as a dispersing medium for the finely divided pyrite. A nutrient solution which would support bacterial growth was the lixiviant. The microorganisms used in the study were autotrophic, iron-oxidizing bacteria obtained from the mine waters of Bingham Canyon, Utah. Studies were made by inoculating the solutions in the percolators with actively growing bacteria and comparing the amount of iron oxidized in the inoculated percolators with the amount of iron oxidized in a sterile, control sample. The effect of autoclaving, mercuric chloride, temperature, light, and carbon dioxide on the oxidative process was studied. The acidity produced in the oxidation of the pyrite was measured. The effect on the activity of the bacteria of ammonium ion and cupric ion was studied. The results of the above studies showed that iron-oxidizing autotrophic bacteria do oxidize iron pyrite. Sterile control samples contained only five percent of the amount of iron in solution that appeared in inoculated solutions. Autoclaving and mecuric chloride killed the micro-organisms and therefore stopped the oxidative process. A reduction in temperature to 0° C. decreased the bacterial activity by an average of eighty-seven per cent. The bacterial activity was increased when the reaction vessels were placed in total darkness. The absence of carbon dioxide or oxygen in the atmosphere of the bacteria slows down the oxidative rate. Results showed that the ammonium ion or the nitrate ion is necessary for the normal growth and activity of the microorganisms. The bacteria in the problem have a tolerance for high concentration of cupric ion. They grew and were active in 500 ppm Cu^++. The possibilities in converting discarded pyrite waste to useful ferric sulfate by biological oxidation should prove to be valuable throughout the Intermountain area.