Physical Sciences and Mathematics Commons^™

Expanding The Scope Of Clickable Azide-Functionalized Nanoclusters To Include Au144, Johanna A. De Jong

Electronic Thesis and Dissertation Repository

Thiolate-protected Au₁₄₄ nanoclusters (NCs) are an intriguing member of the gold NC family. Their geometric structure, distinct electrochemical features, and susceptibility to structural rearrangement under the duress of ligand exchange have been studied. However, there are currently no established protocols for surface modification or tuning of their ligand shells post synthesis. Here, the direct synthesis of three regioisomers of azide-modified Au₁₄₄ NCs with 60 azide moieties, i.e., Au₁₄₄(SC₂H₄C₆H₄-N₃)₆₀, is reported, in which the azide functionality is located at the ortho-, meta-, or …

Combined Geochemical, Mineralogical, And Structural Investigation Of Auriferous Quartz Veins At The Vertigo Target, White Gold District, West-Central Yukon Territory, Canada, James C M Alexander

Electronic Thesis and Dissertation Repository

The Vertigo target on the southwestern JP Ross property is a gold-mineralized showing ~70 km south of Dawson City in the White Gold district, west-central Yukon Territory, Canada. Favourable gold-mineralized zones occur with pathfinder elements As-Ag-Te-Pb-Bi. This study uses digital borehole logging, petrography, electron probe microanalysis, and micro-x-ray fluorescence to evaluate the spatial, geochemical, and mineralogical distribution of Au mineralization at the Vertigo target. Petrographic and structural interpretations are contextualized with synchrotron radiation x-ray diffraction on 120 drill sample pulps. The clustering of diffraction patterns has revealed characteristic signatures of Au-mineralization with structural geometries coincident with the mineralogical clusters. The …

The Relationship Between Visible Gold And Arsenopyrite At The Orenada Zone 4 Deposit, Val D'Or, Quebec, Cassandra Powell

Electronic Thesis and Dissertation Repository

The Orenada Zone 4 deposit is an Archean orogenic gold deposit situated southeast of Val d’Or, Québec in the southeastern Abitibi Greenstone Belt. It is located directly within the Cadillac-Larder-Lake Deformation Zone. Mineralization is hosted within a volcanoclastic horizon of the Cadillac Group where two distinct facies were defined. Both facies underwent a pervasive sericite-chlorite-carbonate±albite alteration assemblage that predates gold mineralization. Gold is associated with two generation of auriferous quartz-carbonate-tourmaline veins and within fractures of corroded arsenopyrite grains, located proximal to the vein walls. A LA-ICP-MS study determined that neither textural type of arsenopyrite displayed refractory gold. Therefore, gold was …

Trace Element Geochemistry And Nd-Sr Isotope Systematics Of Scheelite From The Thunder Creek And 144 Gap Deposits, Timmins, Ontario: Implications For Timing And Genesis Of Gold, Annika Van Kessel

Electronic Thesis and Dissertation Repository

The age of the youngest gold event at the Timmins West Mine is unknown. Scheelite geochemistry and geochronology at the TWM were constrained using WDS and EDS mapping, LA-ICPMS and MC-ICPMS analytical techniques. Trace element analyses by LA-ICPMS revealed scheelites mineralized from a common and oxidized fluid. Samarium-Neodymium isotopic analyses of 15 scheelite grains yielded a linear regression isochron with a corresponding age of 2587 +/- 49 Ma (MSWD = 2.5) and εNdi, calculated from CHUR, of 1.01 ± 0.11 (2SD). A second internal isochron from a single scheelite grain yielded an age of 2516 +/- 88 Ma (MSWD = …

Coinage Metal Chalcogenide Clusters With N-Heterocyclic Carbene Ancillary Ligands, Alex Polgar

Electronic Thesis and Dissertation Repository

This thesis describes the synthesis and characterization of homo- and heterometallic group 11 – group 16 clusters with N-heterocyclic carbene (NHC) ligands. The clusters were prepared from reactive group 11 trimethylsilylchalcogenolate reagents (NHC-M-ESiMe3; M = Cu, Au; E = S, Se, Te) by silane deprotection reactions with phosphine- or phosphite-solubilized group 11 acetates (R3P-M-OAc; M = Cu, Ag, Au). Clusters were characterized by combustion analysis and spectroscopic methods in solution and the solid state. The clusters were phosphorescent at low temperatures with emission energies that depend on the metal/chalcogen composition, ancillary NHC ligand, cluster geometry and nuclearity, and local environment. …

Study On The Surface Features Of Preg-Robbing Carbonaceous Matter During Oxidation Treatment, Mana Pourdasht

Electronic Thesis and Dissertation Repository

Carbonaceous gold ores have the ability to adsorb gold (I) cyanide from leach solutions during processing. This phenomenon, known as preg-robbing, is responsible for poor recoveries as the carbonaceous materials of the ore compete with activated carbon used during the leaching and adsorption phase of processing. Chemical oxidation of carbonaceous materials by different reagents has been utilized to investigate and compare the mechanism of Au (CN)₂ adsorption onto carbonaceous materials prior to and following the treatment.

The procedure for characterization of the carbonaceous materials (plain and modified) in the sample combines the use of several analytical techniques and test …

Metallogenic Setting Of High-Grade Gold Mineralization In The Neoarchean Hearne Craton, Kivalliq Region, Whale Cove, Nunavut, Canada, Mo Asmail

Electronic Thesis and Dissertation Repository

The Pistol Bay Gold Project is located on the northwestern shores of Hudson Bay, in the Tavani Segment of the Neoarchean Kaminak Greenstone Belt in the Hearne Craton of the Western Churchill Province. This project covers several gold prospects whose genesis is hotly debated. The primary objectives of this research are to answer critical questions regarding the nature and timing of gold mineralization. The investigation includes: (1) establish the absolute age of the felsic and mafic intrusions and the relative timing of gold mineralization; (2) document the nature of primary and hydrothermal mineral assemblages related to gold mineralization; and (3) …

An Evaluation Of The Lithologies And Geochemistry Of The Upper Beaver Deposit Of The Kirkland Lake Area, Katherine E. Feick

Electronic Thesis and Dissertation Repository

The Upper Beaver Cu-Au deposit contains a unique style of mineralization in the Larder Lake and Kirkland Lake areas in terms of mineralization, alteration style, and age. This study aims to use company-provided data, supplemented with focused data collection, to evaluate what information can be attained from company-provided geochemical data. The evaluation uses a combination of hand sample, petrographic, geochemical, statistical, and microprobe analytical methods.

Lithogeochemical analyses indicated that the altered igneous host rock is calc-alkaline in composition and is most likely part of the diorite-monzonite suite. Further, exploratory data analysis of Au and Cu mineralization identified that there are …

Coinage Metal Silylphosphido Complexes Stabilized By N-Heterocyclic Carbene Ligands, Bahareh Khalili Najafabadi

Electronic Thesis and Dissertation Repository

N-Heterocyclic carbenes (NHCs) are strong σ-donating ligands and thus, promising candidates for decorating and stabilizing metal-phosphide nanoclusters. While much research has been focused on the coordination of NHC ligands to different coinage metal centers in order to synthesize mononuclear organometallic complexes, their application in nanocluster chemistry has been relatively unexplored. The work described in this thesis involves employment of NHC ligands for stabilizing coinage metal t-butylthiolate and silylphosphido complexes. These complexes are promising molecular precursors for formation of larger NHC-stabilized nanoclusters.

In particular, the ligation of NHCs to [CuS^tBu] and [AgS^tBu] was developed as an …

The Biogeochemical Cycling Of Gold Under Surface And Near-Surface Environmental Conditions, Jeremiah P. Shuster

Electronic Thesis and Dissertation Repository

The mobility of gold at near-surface environmental conditions, e.g., supergene weathering environments, lateritic weathering systems, saline to hypersaline systems and placer gold environments, takes place as oxidised, soluble gold complexes and as reduced elemental gold. The transformation between aqueous and solid states of gold is attributed to the varying geochemical conditions that occur in dynamic environments that are catalysed in part by the biosphere. The primary focus of this research is the investigation of biogeochemical processes that contribute to the cycling of gold using laboratory models to represent various natural systems including chemolithotrophic bacteria, e.g., iron-oxidising bacteria, and heterotrophic sulphate-reducing …