Giant metallic deposits—A century of progress

Abstract not availablePeter Laznick

Giant metallic deposits - a century of exponential progress

Peter Laznick

Robust local thickness estimation of sub-micrometer specimen by 4D-STEM

We present a quantitative four-dimensional scanning transmission electron microscopy (4D-STEM)imaging technique (q4STEM) for local thickness estimation across amorphous specimen such asobtained by focused ion beam (FIB)-milling of lamellae for (cryo-)TEM analysis. Our method isbased on measuring spatially resolved diffraction patterns to obtain the angular distribution of electronscattering, or the ratio of integrated virtual dark and bright field STEM signals, and their quantitativeevaluation using Monte Carlo simulations. The method is independent of signal intensity calibrationsand only requires knowledge of the detector geometry, which is invariant for a given instrument.We demonstrate that the method yields robust thickness estimates for sub-micrometer amorphousspecimen using both direct detection and light conversion 2D-STEM detectors in a coincident FIBSEMand a conventional SEM. Due to its facile implementation and minimal dose requirements,we anticipate that this method will find applications for in-situ thickness monitoring during lamellafabrication of beam-sensitive materials

Assessment of lithium pegmatite ore bodies to determine their amenability to processing for the extraction of lithium

Various processes have been developed using a combination of elevated temperature and chemical treatment processing to recover Li from silicate minerals. To facilitate further process development, a comprehensive understanding of the deportment of Li and associated minerals in ore bodies is essential to allow the industry to predict the response of ore reserves to metallurgical treatment options. This paper describes results from the integrated use of the John de Laeter Centre’s state of the art analytical and mass spectrometry techniques to characterise a selection of Li bearing ore bodies and determine their amenability to potential processing options for the extraction of Li. The mineralogy, mineral associations and liberation characteristics of orebearing and gangue minerals where characterised using by a combination of the TIMA and XRPD studies. The Li content and distribution within minerals were defined using LAM-ICPMS and field emission scanning electron microscopy techniques (ESBD, ToF-SIMS) and atomic probe microscop

Regional-scale Proterozoic IOCG-mineralized breccia systems:\ud examples from the Wernecke Mountains, Yukon, Canada

A large scale Proterozoic breccia system consisting of numerous individual breccia bodies, collectively known as Wernecke Breccia, occurs in north-central Yukon Territory, Canada. Breccias cut Early Proterozoic Wernecke Supergroup sedimentary rocks and occur throughout the approximately 13 km thick deformed and weakly metamorphosed sequence. Iron oxide–copper–gold ± uranium ± cobalt mineralization is associated with the breccia bodies and occurs as veins and disseminations within breccia and surrounding rocks and locally forms the breccia matrix. Extensive sodic and potassic metasomatic alteration occurs within and around breccia bodies and is overprinted by pervasive calcite and dolomite/ankerite, and locally siderite, alteration, respectively. Multiple phases of brecciation, alteration and mineralization are evident. Breccia bodies are spatially associated with regional-scale faults and breccia emplacement made use of pre-existing crustal weaknesses and permeable zones. New evidence indicates the presence of metaevaporitic rocks in lower WSG that may be intimately related to breccia formation. No evidence of breccia-age magmatism has been found to date