Publications
Filter Total Items: 87
Reconnaissance mineral and cathodoluminescence studies of gold occurrences in the Pogo-Black Mountain area, eastern interior Alaska, USA Reconnaissance mineral and cathodoluminescence studies of gold occurrences in the Pogo-Black Mountain area, eastern interior Alaska, USA
The Pogo Au deposit is the largest of a number of gold occurrences in eastern interior Alaska, that occur along a broad trend from west of Pogo to Black Mountain. Some of these occurrences are hosted in amphibolite facies gneisses and others in mid-Cretaceous igneous rocks that intruded the older metamorphic rocks. All occurrences contain arsenopyrite and pyrite. Whole rock geochemical...
Authors
Garth Graham, Erin Marsh, Heather Lowers, Ryan D. Taylor
Characterizing lung particulates using quantitative microscopy in coal miners with severe pneumoconiosis Characterizing lung particulates using quantitative microscopy in coal miners with severe pneumoconiosis
Context.— Current approaches for characterizing retained lung dust using pathologists' qualitative assessment or scanning electron microscopy with energy-dispersive spectroscopy (SEM/EDS) have limitations. Objective.— To explore polarized light microscopy coupled with image-processing software, termed quantitative microscopy–particulate matter (QM-PM), as a tool to characterize in situ...
Authors
Jeremy Hua, Carlyne Cool, Heather Lowers, Leonard Go, Lauren Zell-Baran, Emily Sarver, Kirsten Almberg, Kathy Pang, Susan Majka, Angela Franko, Naseema Vorajee, Robert Cohen, Cecil Rose
Formation of orogenic gold deposits by progressive movement of a fault-fracture mesh through the upper crustal brittle-ductile transition zone Formation of orogenic gold deposits by progressive movement of a fault-fracture mesh through the upper crustal brittle-ductile transition zone
Orogenic gold deposits are comprised of complex quartz vein arrays that form as a result of fluid flow along transcrustal fault zones in active orogenic belts. Mineral precipitation in these deposits occurs under variable pressure conditions, but a mechanism explaining how the pressure regimes evolve through time has not previously been proposed. Here we show that extensional quartz...
Authors
Miguel Nassif, Thomas Monecke, T. Reynolds, Yvette D. Kuiper, Richard Goldfarb, Sandra Piazolo, Heather Lowers
Cathodoluminescence response of barite at room and liquid nitrogen temperatures Cathodoluminescence response of barite at room and liquid nitrogen temperatures
Rare earth element (REE) enrichment in the Elk Creek carbonatite, Nebraska USA, is comparable to ore grade enrichment in carbonatite-hosted REE deposits[1]. Petrographic examination of textures documents a complex history of crystallization, brecciation, recrystallization, oxidation, and near surface alteration. Barite (BaSO4) is present in most units, including REE-enriched zones, such...
Authors
Heather Lowers, Colin MacRae, Nick Wilson, Philip Verplanck
Quantitative and qualitative correlation of CL and X-ray signals in Cr-bearing jade from Chichén-Itzá Archaeological Zone, Mexico Quantitative and qualitative correlation of CL and X-ray signals in Cr-bearing jade from Chichén-Itzá Archaeological Zone, Mexico
No abstract available.
Authors
E Vicenzi, Thomas Lam, Heather Lowers, Paul Carpenter, David Adams
Demonstration of a novel quantitative microscopy technique for automated characterization of in situ particulate matter in coal miners with progressive massive fibrosis Demonstration of a novel quantitative microscopy technique for automated characterization of in situ particulate matter in coal miners with progressive massive fibrosis
Rationale: Increasing exposure to respirable crystalline silica (RCS) linked to changes in mining production processes has been implicated in the resurgence of severe lung disease in U.S. coal miners. Lung mineralogy can provide insight into particle pathogenesis. However, standard approaches to characterizing in situ particulate matter (PM) by pulmonary pathologists have poor inter...
Authors
Jeremy Hua, Lauren Zell-Baran, L. Go, Carlyne Cool, Heather Lowers, K. Almberg, Emily Sarver, Susan Majka, Kathy Pang, R. Cohen, Cecil Rose
Pathology and mineralogy demonstrate respirable crystalline silica is a major cause of severe pneumoconiosis in US coal miners Pathology and mineralogy demonstrate respirable crystalline silica is a major cause of severe pneumoconiosis in US coal miners
Rationale: The reasons for resurgent coal workers’ pneumoconiosis and its most severe forms, rapidly progressive pneumoconiosis and progressive massive fibrosis (PMF), in the United States (US) are not yet fully understood. Objective: To compare the pathologic and mineralogic features of contemporary coal miners suffering severe pneumoconiosis to their historical counterparts. Methods...
Authors
R. Cohen, Cecil Rose, L. Go, Lauren Zell-Baran, K. Almberg, Emily Sarver, Heather Lowers, C. Iwaniuk, S. Clingerman, D. Richardson, J.L. Abraham, Carlyne Cool, A. Franko, A.F. Hubbs, J. Murray, M.S. Orandle, S. Sanyal, N.I. Vorajee, E.L. Petsonk, R. Zulfikar, F.H. Green
Approach for quantifying rare Earth elements at low keV Approach for quantifying rare Earth elements at low keV
The challenges of analyzing bastnaesite (REECO3F) and hydroxylbastnaesite (REECO3OH) include beam sensitivity, quantification of light elements in a heavy element matrix, the presence of elements that cannot be analyzed with EPMA (H), and the use of x-ray lines whose physical constants are not well known. To overcome some of these challenges, Ca, La, Ce, Pr, Nd, and Sm were analyzed at...
Authors
Heather Lowers
The complexity of mudstone diagenesis - some insight from the Tøyen Formation, Lower to Middle Ordovician, southern Sweden The complexity of mudstone diagenesis - some insight from the Tøyen Formation, Lower to Middle Ordovician, southern Sweden
The Lower to Middle Ordovician Tøyen Shale in southern Sweden, a biostratigraphically well-dated siliciclastic mudstone unit, shows 18 distinct authigenic cements that include sulfides, carbonates, silicates, clays, and phosphates. Marcasite, sphalerite, galena, and six texturally distinct types of pyrite characterize the sulfides whereas only one type of dolomite and three different...
Authors
Sven Egenhoff, Neil Fishman, Heather Lowers, Per Ahlberg
Geochemistry of hematite veins in IOA-IOCG deposits of SE Missouri, USA: Relation to felsic magmatism and caldera lakes Geochemistry of hematite veins in IOA-IOCG deposits of SE Missouri, USA: Relation to felsic magmatism and caldera lakes
The paragenesis, textures, and chemical compositions of secondary hematite in regional potassic altered rhyolites, four IOA deposits, the sedimentary iron deposit at Pilot Knob and the Boss IOCG deposit in SE Missouri were determined and compared to primary magnetite from the IOA and IOCG deposits. Magnetite is composed of elements characteristics of mafic to intermediate intrusions...
Authors
Corey Meighan, Albert Hofstra, Erin Marsh, Heather Lowers, Alan Koenig
Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions Absence of magnetite microlites, geochemistry of magnetite veins and replacements in IOA deposits, SE Missouri, USA: Relations to intermediate intrusions
The paragenesis, textures, and chemical compositions of magnetite in two mafic to intermediate intrusions and four IOA deposits in SE Missouri were studied to discriminate between igneous and hydrothermal sources. In this study, we found that replacement magnetite with mineral inclusion-rich cores yields erroneously high Ti, Al, Si, Mg, and Mn contents as determined by EMP and LA-ICP-MS...
Authors
Corey Meighan, Albert Hofstra, David Adams, Erin Marsh, Heather Lowers, Alan Koenig
Method to characterize inorganic particulates in lung tissue biopsies using field emission scanning electron microscopy Method to characterize inorganic particulates in lung tissue biopsies using field emission scanning electron microscopy
Humans accumulate large numbers of inorganic particles in their lungs over a lifetime. Whether this causes or contributes to debilitating disease over a normal lifespan depends on the type and concentration of the particles. We developed and tested a protocol for in situ characterization of the types and distribution of inorganic particles in biopsied lung tissue from three human groups...
Authors
Heather Lowers, George Breit, Matthew Strand, Renee Pillers, Gregory Meeker, Todor Todorov, Geoffrey Plumlee, Ruth E. Wolf, Maura Robinson, Jane Parr, Robert Miller, Steve Groshong, Francis Green, Cecile Rose