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Heather A Lowers

Heather Lowers is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.

Science and Products

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SEM image of carbonatite

Critical Elements in Carbonatites: From Exploration Targets to Element Distribution

Critical elements are essential to the modern economy and have potential supply chain disruptions, but compared to most base and precious metals, little work has been done in understanding ore-grade enrichments. Carbonatites are the primary source of the worlds light rare earth elements and niobium, and a potential source for heavy rare earths, scandium, tantalum, and thorium. Project objectives...
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center
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Critical Elements in Carbonatites: From Exploration Targets to Element Distribution

Critical elements are essential to the modern economy and have potential supply chain disruptions, but compared to most base and precious metals, little work has been done in understanding ore-grade enrichments. Carbonatites are the primary source of the worlds light rare earth elements and niobium, and a potential source for heavy rare earths, scandium, tantalum, and thorium. Project objectives...
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Old JEOL Scanning Electron Microscope.

Denver Microbeam Laboratory: Mineral Resources Research Support

The USGS Denver Microbeam Laboratory provides chemical analysis and characterization of rocks, minerals, and environmental samples in support of a wide variety of USGS projects related to mineral resources, including research projects funded by the USGS Mineral Resources Program. The research applications for these projects range from mineral resource research and assessments, to geologic mapping...
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory
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Denver Microbeam Laboratory: Mineral Resources Research Support

The USGS Denver Microbeam Laboratory provides chemical analysis and characterization of rocks, minerals, and environmental samples in support of a wide variety of USGS projects related to mineral resources, including research projects funded by the USGS Mineral Resources Program. The research applications for these projects range from mineral resource research and assessments, to geologic mapping...
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Lung Tissue

Department of Defense Lung Study

Between 2003 and the present, 2.2 million U.S. military personnel have been deployed to Iraq and Afghanistan. These deployers have been variably exposed to desert dusts, smoke from burn pits, and urban particulate matter, and some have developed constrictive bronchiolitis. A study was undertaken to determine what, if any, markers were statistically different among biopsied lung tissue sections...
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Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory
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Department of Defense Lung Study

Between 2003 and the present, 2.2 million U.S. military personnel have been deployed to Iraq and Afghanistan. These deployers have been variably exposed to desert dusts, smoke from burn pits, and urban particulate matter, and some have developed constrictive bronchiolitis. A study was undertaken to determine what, if any, markers were statistically different among biopsied lung tissue sections...
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Filter Total Items: 20

Trace element chemistry of sulfides and quartz, in situ sulfur isotope values of sulfides, cathodoluminescence of quartz, fluid inclusion microthermometry and raman, and radiogenic isotope and whole rock geochemistry from the Stibnite-Yellow Pine district

This dataset is a collection of geochemical data on samples from the Stibnite-Yellow Pine district of Idaho. The datasets include: whole rock geochemistry; lead, strontium and neodymium isotope chemistry of sulfides and whole rock samples by isotope dilution-thermal-mass spectrometry (ID-TIMS); in situ sulfur isotope chemistry of sulfides by laser ablation-multi collector-inductively coupled-mass
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Geology, Geophysics, and Geochemistry Science Center

Microanalysis of samples collected from sandstone-hosted uranium and vanadium deposits in the Colorado Plateau: Utah, New Mexico and Colorado, USA

These data are microanalyses of 91 polished thin sections that were examined using a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) to identify minerals and observe their relationships at high magnification. Samples are from the Triassic Chinle and Jurassic Morrison Formations and adjacent units, which are the main hosts for sandstone-hosted uranium-vanadi
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Central Energy Resources Science Center

Data release of geochemistry and geochronology for Proterozoic rocks in southwestern Colorado and rocks from drill core from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska

This U.S. Geological Survey (USGS) data release provides whole rock major, minor, and trace element geochemical data, mineral chemistry, and monazite and xenotime geochronology for Proterozoic rocks in the Needle Mountains of southwestern Colorado and for Proterozoic rocks sampled from drill cores from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska. Samples from the Needle Mountain
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Geosciences and Environmental Change Science Center

Denali Fault Zone Field, Microvein, and Microbeam Data, Kluane Ranges, Yukon, Canada

Detailed geologic mapping and sample collection was conducted in rare bedrock exposures of the Denali fault zone during the summer months of 2013, 2014, and 2015 by the U.S. Geological Survey. Data include measurements of structural geologic orientations and documentation of fault zone and host rock characteristics. Representative samples were selected for measurements of fault vein attributes and
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

Characteristics of Dust Associated with the Development of Rapidly Progressive Pneumoconiosis and Progressive Massive Fibrosis

Research and surveillance reports have documented a significant increase in coal workers' pneumoconiosis, including the most severe forms of progressive massive fibrosis and rapidly progressive pneumoconiosis in U.S. coal miners, particularly those in Appalachian coalfields. Several possible explanations for these observations include excessive exposures to total respirable dust, increased exposur
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Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

Microanalysis of samples collected from the Sulfur Springs Draw calcrete-type uranium deposit in the Southern High Plains, Texas, USA

This data release presents the results of microanalysis of 2 samples SSD15_01A (1 thin section and 1 composite chip sample), and SSD15_01B (1 thin section). The samples were collected in 2015 by U.S. Geological Survey geologists Bradley Van Gosen and Susan Hall from surface exposures of uranium mineralization in Sulfur Springs Draw, in Martin County, Texas (Van Gosen and Hall, 2017). The samples w
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Central Energy Resources Science Center

Geochemistry of rocks and rock fabric data near the hanging wall contact to the Reef Package, Stillwater Complex, Montana, USA

The Reef Package is a sequence of coarse-grained cumulates that host the J-M Reef Pd-Pt deposit in the Stillwater Complex of Montana. The top of the Reef Package marks the top of economic-grade platinum-group element mineralization and is identified by a distinct change in rock fabric, from the coarse-grained rocks of the Reef Package to finer-grained cumulates in the hanging wall. This dataset ta
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Mineral Resources Program, Geology, Minerals, Energy, and Geophysics Science Center

Geochemical data for the Elk Creek alkaline complex, southeast Nebraska

This U.S. Geological Survey (USGS) data release contains analytical data from a suite of rock and mineral samples collected from drill core within the Elk Creek alkaline complex, southeast Nebraska. This complex hosts the Elk Creek carbonatite, a multilithologic carbonatite enriched in niobium, rare earth elements (REEs), scandium, and titanium. Mineralized carbonatites are the world's prim
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

Spectroscopy of Expanded Vermiculite Products and Insulation

This dataset contains descriptions and analytical data (i.e., electron microprobe, X-ray diffraction, spectral reflectance, and scanning electron microprobe analyses) for unexpanded and expanded vermiculite samples. These data are provided for 52 samples of vermiculite attic insulation, horticultural products, aggregate, and packing materials derived from mines near Enoree, South Carolina; Libby,
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory, Spectroscopy Lab

Electron Probe Microanalyses of apatite, rutile, and titanite from stream sediment and rock samples in the eastern Tanacross quadrangle, eastern Alaska

The exploration for porphyry deposits in some parts of Alaska may require unconventional exploration geochemical methods, depending on type of cover. The Taurus deposit and others in the region are mostly concealed by residual soils that in part include ash and loess, and therefore traditional stream sediment samples typically contain subdued geochemical signatures. Indicator mineral studies inclu
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

Table of Electron Probe Microanalyses of Native Copper and Sulfide Minerals from the White Pine Sediment-hosted Copper Deposit, Michigan

This data release provides electron microprobe geochemical data that was collected as part of a scoping study to evaluate whether unconventional critical element resources may be associated with sediment-hosted copper systems in the Midcontinent Rift. We report abundances of trace elements in native copper and sulfide minerals in 12 thin sections from samples of the Mesoproterozoic lower Nonesuch
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

Table of Electron Probe Microanalyses of Cassiterite from the Sullivan Pb-Zn-Ag Deposit, British Columbia

This dataset contains results from electron microprobe analyses of cassiterite from the Sullivan Pb-Zn-Ag deposit, British Columbia. These data were collected from two samples and may not reflect the overall variability present at the deposit. An ASCII text file of results is provided in comma-separated by value (csv) format. The file has the name "2019-07-09_Sullivan_Cassiterite".
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory
microscopic gold and lead particles
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Microscopic Gold and Lead Particles
Image: Fuzzy Balls
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Fuzzy Balls
Filter Total Items: 84

Monazite and xenotime petrochronologic constraints on four Proterozoic tectonic episodes and ca. 1705 Ma age of the Uncompahgre Formation, southwestern Colorado, USA

The Proterozoic tectonic evolution of the south-western USA remains incompletely understood due to limited constraints on the timing and conditions of the tectono-metamorphic phases and depositional age of metasedimentary successions. We integrated multi-scale compositional mapping, petrologic modeling, and in situ geochronology to constrain pressure-temperature-time paths from samples of Paleopro
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Ian William Hillenbrand, Michael L. Williams, Karl E. Karlstrom, Amy K. Gilmer, Heather A. Lowers, Michael J. Jercinovic, Kaitlyn Suarez, Amanda (Kate) Souders
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Geology, Geophysics, and Geochemistry Science Center, Geosciences and Environmental Change Science Center

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 dust in lung t
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Jeremy T. Hua, Carlyne D. Cool, Heather A. Lowers, Leonard H. T. Go, Lauren M. Zell-Baran, Emily A. Sarver, Kirsten S. Almberg, Kathy D. Pang, Susan M. Majka, Angela D. Franko, Naseema I. Vorajee, Robert A. Cohen, Cecil S. Rose
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Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

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 veins at the G
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Miguel Tavares Nassif, Thomas Monecke, T. James Reynolds, Yvette D. Kuiper, Richard J. Goldfarb, Sandra Piazolo, Heather A. Lowers
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

Quantitative and qualitative correlation of CL and X-ray signals in Cr-bearing jade from Chichén-Itzá Archaeological Zone, Mexico

No abstract available.
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E Vicenzi, Thomas Lam, Heather A. Lowers, Paul K. Carpenter, David T. Adams
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Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

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 that it ma
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Heather A. Lowers, Colin MacRae, Nick Wilson, Philip Verplanck
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

The geochemical and textural transition between the Reef Package and its hanging wall, Stillwater Complex, Montana, USA

The highest grade Pd-Pt deposit on Earth, the J-M Reef, is hosted in coarse-grained to pegmatoidal cumulates called the Reef Package. Decades of mine development of the J-M Reef have revealed that a distinct discontinuity in rock fabric marks the top of the rock unit that hosts economic-grade sulfide mineralization. Mine geologists refer to this discontinuity as the hanging wall contact. This cont
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M. Christopher Jenkins, James E. Mungall, Michael L. Zientek, Kevin Butak, Sam R. Corson, Paul Holick, Ryan McKinley, Heather A. Lowers
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Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center

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-rater comparab
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Jeremy T. Hua, Lauren M. Zell-Baran, L. H. Go, Carlyne D. Cool, Heather A. Lowers, K. S. Almberg, Emily A. Sarver, Susan M. Majka, Kathy D. Pang, R. A. Cohen, Cecil S. Rose
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Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

The dynamic floor of Yellowstone Lake, Wyoming, USA: The last 14 k.y. of hydrothermal explosions, venting, doming, and faulting

Hydrothermal explosions are significant potential hazards in Yellowstone National Park, Wyoming, USA. The northern Yellowstone Lake area hosts the three largest hydrothermal explosion craters known on Earth empowered by the highest heat flow values in Yellowstone and active seismicity and deformation. Geological and geochemical studies of eighteen sublacustrine cores provide the first detailed syn
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Lisa Ann Morgan Morzel, Wayne (Pat) Shanks, Kenneth L. Pierce, Nels Iverson, Christopher Schiller, Sabrina R. Brown, Petra Zahajska, Rosine Cartier, Ron Cash, James Best, Cathy Whitlock, Sherilyn Fritz, William Benzel, Heather A. Lowers, D. A. Lovalvo, J. M. Licciardi
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Volcano Hazards Program, Geology, Geophysics, and Geochemistry Science Center, Geology, Minerals, Energy, and Geophysics Science Center, Volcano Science Center

Petrogenesis and rare earth element mineralization of the Elk Creek carbonatite, Nebraska, USA

Although carbonatites are the primary source of the world’s rare earth elements (REEs), the processes responsible for ore-grade REE enrichment in carbonatites are still poorly understood. In this study, we present a petrologic, geochemical, and isotopic evaluation of the Elk Creek carbonatite in southeast Nebraska to constrain the origin of REE mineralization. The Elk Creek carbonatite is a multil
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Philip Verplanck, G. Lang Farmer, Richard M. Kettler, Heather A. Lowers, Craig A. Johnson, Alan E. Koenig, Michael J. Blessington
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center

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: Lung pathol
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R. A. Cohen, Cecil S. Rose, L. H. Go, Lauren M. Zell-Baran, K. S. Almberg, Emily A. Sarver, Heather A. Lowers, C. Iwaniuk, S. Clingerman, D. Richardson, J.L. Abraham, Carlyne D. Cool, A. Franko, A.F. Hubbs, J. D. Murray, M.S. Orandle, S. Sanyal, N.I. Vorajee, E.L. Petsonk, R. Zulfikar, F.H. Green
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Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

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 15 keV acce

Authors
Heather A. Lowers
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Mineral Resources Program, Geology, Geophysics, and Geochemistry Science Center, Denver Microbeam Laboratory

Pyritization history in the middle to upper Cambrian Alum Shale, Scania Sweden: Evidence for ongoing diagenetic processes

Detailed diagenetic studies of the late Cambrian Alum Shale in southern Sweden were undertaken across an interval that includes the peak Steptoean Positive Carbon Isotope Excursion (SPICE) event to evaluate the pyrite mineralization history in the formation. Samples were collected from the Andrarum-3 core (Scania, Sweden); here the Alum was deposited in the distal, siliciclastic mudstone-rich end
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Neil S. Fishman, Sven O. Egenhoff, Heather A. Lowers, Adam Boehlke, Per Ahlberg
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Geology, Geophysics, and Geochemistry Science Center
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How an Electron Microprobe Helps Find Minerals (and Makes Pretty Pictures!)

Today’s high-end electronics increasingly rely on mineral commodities...and research into those mineral commodities is increasingly using high-end...

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Investigating Lung Disease in Military Veterans

Six years ago, veterans returning from Iraq and Afghanistan had trouble breathing normally. The list of potential causes that soldiers were exposed to...

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