Browsing by Subject "Gold"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Comparative Geology, Stratigraphy, and Lithogeochemistry of the Five Mile Lake, Quartz Hill, and Skeleton Lake VMS Occurrences, Western Vermilion District, NE Minnesota
    (University of Minnesota Duluth, 2002-12) Hudak, George J; Heine, John J; Newkirk, Trent; Odette, Jason; Hauck, Steven A
  • Thumbnail Image
    Item
    Development of Aryl Decarboxylative Functionalization Reactions
    (2021-05) Daley, Ryan
    New synthetic methods are needed to address the tremendous environmental costs associated with fine chemical production. Towards this goal, my graduate research has focused on designing and developing new decarboxylative cross-coupling methods. These reactions replace high energy, unstable, and expensive organometallic nucleophiles with low energy and readily available (hetero)aryl carboxylic acids. First, I reported an efficient palladium catalyzed salt-free decarboxylative allylation of allylic carbonates, which was designed to generate base in-situ. Next, I advanced a method for the decarboxylative cross-coupling of inexpensive aryl chlorides. The mechanism of this transformation was investigated and gave insights that enabled an increase in catalyst performance. More recently, I developed the first gold catalyzed decarboxylative cross-coupling of aryl iodides. This reaction overcame limitations associated both with decarboxylative couplings and reactions involving redox events at gold. I then investigated the mechanism this reaction with the goal of surmounting the current limitations of this promising technology.
  • Thumbnail Image
    Item
    Electrochemical analysis of Shewanella oneidensis engineered to bind gold electrodes.
    (2011-03) Kane, Aunica L.
    Three-electrode bioreactors can be utilized to examine the mechanisms involved in electron flow from bacteria to insoluble electron acceptors and allow these processes to be analyzed quantitatively. As an electrode, gold is an ideal surface to study the electrophysiology occurring during extracellular respiration; yet previous research has shown that Shewanella is resistant to colonization on gold surfaces. Therefore, the goal of this work was to direct adhesion of Shewanella oneidensis to gold surfaces via cell surface display of a modified E. coli outer membrane protein, LamB, and a gold-binding peptide (5rGBP) to encourage microbe-electrode interaction, improve whole-cell biocatalytic systems, and increase overall current production. Expression of LamB-5rGBP increased the affinity of Shewanella for gold surfaces, but also led to the displacement of certain outer membrane components required for extracellular electron transport. Displacement of these outer membrane proteins decreased the rate at which Shewanella was able to reduce both insoluble iron and riboflavin. Expression of LamB-5rGBP, although effectively increasing attachment to gold, did not greatly increase current production in gold-electrode bioreactors.
  • Thumbnail Image
    Item
    The History of Gold Exploration In Minnesota
    (University of Minnesota Duluth, 2011) Severson, Mark J
    This report is more or less an atlas with regard to gold exploration in the Archean rocks of northern Minnesota. The main objective of this study is to compile all available information (maps, assays, reports, etc.) from the historical records to produce a “Guidebook” that describes “who did what, where, and how, and what did they find” regarding the gold exploration history of northeastern Minnesota. In essence, detailed “due diligence” checks have been performed in this report, and the results are described for 62 orogenic gold prospects as follows: western Vermilion District with 29 gold prospects; Cook area with nine gold prospects; northeastern Itasca County area with nine gold prospects; Rainy Lake area with four gold prospects; Virginia Horn area with ten prospects; and the Koochiching-Beltrami-Roseau-Lake of the Woods counties area (no significant prospects). Out of 23 gold prospects that were extensively drilled and/or trenched in the western Vermilion District, the best prospects that returned the highest gold values, and collectively the most mineralized zones, are located in the area bordered by the Vermilion Fault and Mud Creek Shear zone. Most of these prospects are associated with subsidiary shear zones and/or rheological contacts on the edges of iron-formation lenses. Shear zone-hosted gold was also explored for in some detail elsewhere in the western Vermilion District at Spaulding Bay, Murray, and Eagles Nest Shear zones. Exploration for gold took place the most extensively, and for the longest period, at the Shagawa Lake stock. There are very few conclusions that can be drawn from the data that are available for the Cook area. The data suggest that the best gold potential is present at the Linden Grove area, where several faults converge and structural preparation would be increased. A review of the gold prospects in Itasca County suggests that significant gold shows are associated with an iron-formation trend in the Wilson Lake sequence. In almost all cases, the high gold values are associated with iron-formation, especially structurally-prepared and sulfide-replaced zones. Glacial overburden sampling campaigns have reiterated this gold-to-iron-formation connection. A review of the exploration activities conducted at the gold prospects in the Rainy Lake area suggests that significant gold anomalies are present within both the “iron-formation” unit of Day (1990) and the Rainy Lake-Seine River Fault Zone. However, the gold values obtained during drilling generally occur as isolated values in a select number of drill holes. Exploration to the west of Rainy Lake in the Koochiching-Beltrami-Roseau-Lake of the Woods area is confined to scattered drill holes that targeted geophysical anomalies. Exploration in the Virginia Horn has to date identified a “small but low-grade” gold deposit associated with a hypabyssal quartzofeldspathic intrusion informally known as the Viking porphyry. Visible gold, often with associated arsenopyrite, is present in quartz veins in the porphyry. However, gold shows are also present in the surrounding rocks, and more drilling is needed to fully assess the potential of the Virginia Horn.
  • Thumbnail Image
    Item
    Non-ferrous Geology along the Highway 53 Relocation near Virginia, MN
    (University of Minnesota Duluth, 2015) Heine, John J; Patelke, Marsha Meinders; Post, Sara P; Maly, Craig C
    This report outlines the non-ferrous work done in the area of the Highway 53 relocation near Virginia, MN. At the request of the mineral lease holder (Vermilion Gold Inc.), an examination of the gold potential in the area of the new road was completed. Vermilion Gold Inc. located ten exploration diamond drill hole sites which they believed were necessary to characterize the area. Drilling occurred during fall 2013 and was conducted by Idea Drilling. The drilling and subsequent work by Natural Resource Research Institute, University of Minnesota Duluth (NRRI) was funded by the Minnesota Department of Transportation (Mn/DOT) as part of the relocation work for the highway. Logging and sample preparation were completed at the NRRI Coleraine Minerals Research Laboratory (CMRL) in Coleraine, MN.
  • Thumbnail Image
    Item
    Structural, Kinematic, and Hydrothermal Fluid Investigation of the Gold-Bearing Murray Shear Zone, northeastern Minnesota
    (2009-10) Johnson, Thomas Kenneth
    Gold mineralization within Archean granite greenstone terrains of northeastern Minnesota continues to be enigmatic despite its known association to shear zones, faults, and folds. As products of deformational events shear zones, faults, and folds localize fluid transportation and ultimately gold mineralization. Their kinematic history and structural architecture contain important clues about the genesis, characteristics, and mechanics of ore-bearing fluids. The Murray Shear Zone of northeastern Minnesota hosts subeconomic gold in a unique structural setting. Evidence exists in support of shear zone-hosted gold mineralization that coincides with established models for well-known and profitable gold deposits of other Archean greenstone terrains. This thesis presents a structural, kinematic, and hydrothermal fluid investigation of the Murray Shear Zone with implications for gold mineralization. Field and laboratory research such as structural mapping, analysis of thin sections for microstructures and deformation mechanisms, and geochemical study was conducted to provide a comprehensive look at gold mineralization processes of the Murray Shear Zone.
  • Thumbnail Image
    Item
    Understanding Fraud in the Silver Mining Districts of the Western United States in the Second Half of the 19th Century
    (2016-02-18) Miller, Baylee, A.
    The mining industry has recorded many events of large fraud. The Comstock Lode in particular had several different types of fraud committed at different stages in the time frame of a mine in operation. The history of the Comstock Lode is important to understanding how lies can be believed, and has an impact on current day investments. Enormous cases of fraud have occurred since the Comstock Lode, and the methods of fraud are largely similar. Identifying where and how fraud occurs that leads to it going unnoticed is necessary for prevention. Additionally, rules and regulations need to be made and followed to ensure that claims are indeed what they appear to be. The Comstock Lode will be the main area of focus due to the typical occurrence of fraud in this region during its development.