Microscopic gold and lead particles surrounded by organic and phosphorus-rich material in a municipal biosolids sample (combined surface topography and atomic weight images).
Heather A Lowers
Heather Lowers is a Research Geologist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Critical Elements in Carbonatites: From Exploration Targets to Element Distribution
Denver Microbeam Laboratory: Mineral Resources Research Support
Department of Defense Lung Study
Method development for determination of trace amounts of silicon in hydrofluoric acid digests of biological samples and lung biopsy tissues by ICP-MS
Stable isotope data for sulfur, oxygen, and hydrogen in minerals and gases and electron microprobe data for minerals from Sulphur Bank mercury mine, Lake County, California
Data release of isotope geochemistry, mineral chemistry, and geochronology for a Proterozoic paragneiss sampled from drill core from North Dakota
Geochemical Analysis of Bulk Dust and Human Respiratory Cells and Fluids in Research on Deployment-related Lung Injury
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
Microanalysis of samples collected from sandstone-hosted uranium and vanadium deposits in the Colorado Plateau: Utah, New Mexico and Colorado, USA
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
Denali Fault Zone Field, Microvein, and Microbeam Data, Kluane Ranges, Yukon, Canada
Characteristics of Dust Associated with the Development of Rapidly Progressive Pneumoconiosis and Progressive Massive Fibrosis
Microanalysis of samples collected from the Sulfur Springs Draw calcrete-type uranium deposit in the Southern High Plains, Texas, USA
Geochemistry of rocks and rock fabric data near the hanging wall contact to the Reef Package, Stillwater Complex, Montana, USA
Geochemical data for the Elk Creek alkaline complex, southeast Nebraska
Microscopic gold and lead particles surrounded by organic and phosphorus-rich material in a municipal biosolids sample (combined surface topography and atomic weight images).
Backscattered electron image of radiating fibers of kaolinite growing in volcanic rock altered by fluids connected to hot springs near Lassen Volcanic National Park. Associated with the kaolinite are rounded masses of silica and iron oxides (bright areas) that formed from pyrite. The composition and textures help us evaluate the origin of ore deposits and
Backscattered electron image of radiating fibers of kaolinite growing in volcanic rock altered by fluids connected to hot springs near Lassen Volcanic National Park. Associated with the kaolinite are rounded masses of silica and iron oxides (bright areas) that formed from pyrite. The composition and textures help us evaluate the origin of ore deposits and
Trace silicon determination in biological samples by inductively coupled plasma mass spectrometry (ICP-MS): Insight into volatility of silicon species in hydrofluoric acid digests for optimal sample preparation and introduction to ICP-MS
Paleoproterozoic reworking of Archean crust and extreme back-arc metamorphism in the enigmatic southern Trans-Hudson orogen
Hydrothermal monazite and xenotime chemistry as genetic discriminators for intrusion-related and orogenic gold deposits: Implications for an orogenic origin of the Pogo gold deposit, Alaska
Attempts to geochemically distinguish between metamorphic-hydrothermal systems that form orogenic gold deposits and both reduced and oxidized magmatic-hydrothermal systems using isotopes or metal associations have proven ambiguous, particularly for orogenic gold and reduced intrusion-related gold systems. The absence of conclusive geochemical discriminators and the overlap in geologic characterist
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 trends dist
The Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite
Carbonatite-hosted rare earth element (REE) deposits are the primary source of the world’s light REEs and have the potential to be a source of heavy REEs. The Mount Weld REE deposit in Western Australia is hosted in a lateritic sequence that reflects supergene enrichment of the underlying carbonatite complex. Similar to other carbonatite-related ore deposits, ore from Mount Weld displays extreme l
Hyperspectral cathodoluminescence and quantitative EPMA mapping of angrite northwest Africa 15507
Monazite and xenotime petrochronologic constraints on four Proterozoic tectonic episodes and ca. 1705 Ma age of the Uncompahgre Formation, southwestern Colorado, USA
Characterizing lung particulates using quantitative microscopy in coal miners with severe pneumoconiosis
Formation of orogenic gold deposits by progressive movement of a fault-fracture mesh through the upper crustal brittle-ductile transition zone
Quantitative and qualitative correlation of CL and X-ray signals in Cr-bearing jade from Chichén-Itzá Archaeological Zone, Mexico
Cathodoluminescence response of barite at room and liquid nitrogen temperatures
The geochemical and textural transition between the Reef Package and its hanging wall, Stillwater Complex, Montana, USA
Science and Products
- Science
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...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...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... - Data
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Method development for determination of trace amounts of silicon in hydrofluoric acid digests of biological samples and lung biopsy tissues by ICP-MS
A method was described for determination of trace levels of silicon by inductively coupled plasma mass spectrometry (ICP-MS) from hydrofluoric (HF) digests of biological samples. The volatility of silicon in HF digests was examined with synthetic solutions as well as soil and mine waste samples. A digestion scheme was optimized to achieve complete dissolution, avoid loss of volatile silicon specieStable isotope data for sulfur, oxygen, and hydrogen in minerals and gases and electron microprobe data for minerals from Sulphur Bank mercury mine, Lake County, California
Stable isotope compositions (the ratios deuterium/hydrogen, oxygen-18/oxygen-16, and sulfur-34/sulfur-32) are reported for alunite, jarosite, kaolinite, silica, cinnabar, marcasite, and native sulfur from outcrops in and around the workings of the Sulphur Bank mercury mine, Lake County, California, and chemical compositions are reported, from electron microprobe analyses, for alunite and buddingtoData release of isotope geochemistry, mineral chemistry, and geochronology for a Proterozoic paragneiss sampled from drill core from North Dakota
This U.S. Geological Survey (USGS) data release provides whole rock isotope geochemistry, zircon hafnium isotope geochemistry, feldspar mineral chemistry, and zircon, monazite, and xenotime geochronology for a paragneiss sampled from a drill core from North Dakota. The sample was collected from the 9-11R E-M Larson well in order to constrain the depositional age, provenance, metamorphic history, aGeochemical Analysis of Bulk Dust and Human Respiratory Cells and Fluids in Research on Deployment-related Lung Injury
Multiple techniques including, x-ray diffraction, scanning electron microscopy, laser diffraction particle analysis, and inductively coupled plasma spectrometry, were used to characterize the morphology and composition of dust used for biological studies as well as lung tissue from rats, personnel deployed to Southwest Asia, and control samples. The data presented in this release are organized inTrace 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-massMicroanalysis 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-vanadiData 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 MountainDenali 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 andCharacteristics 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 exposurMicroanalysis 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 wGeochemistry 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 taGeochemical 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 - Multimedia
Microscopic Gold and Lead Particles
Microscopic gold and lead particles surrounded by organic and phosphorus-rich material in a municipal biosolids sample (combined surface topography and atomic weight images).
Microscopic gold and lead particles surrounded by organic and phosphorus-rich material in a municipal biosolids sample (combined surface topography and atomic weight images).
Fuzzy BallsBackscattered electron image of radiating fibers of kaolinite growing in volcanic rock altered by fluids connected to hot springs near Lassen Volcanic National Park. Associated with the kaolinite are rounded masses of silica and iron oxides (bright areas) that formed from pyrite. The composition and textures help us evaluate the origin of ore deposits and
Backscattered electron image of radiating fibers of kaolinite growing in volcanic rock altered by fluids connected to hot springs near Lassen Volcanic National Park. Associated with the kaolinite are rounded masses of silica and iron oxides (bright areas) that formed from pyrite. The composition and textures help us evaluate the origin of ore deposits and
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Filter Total Items: 90
Trace silicon determination in biological samples by inductively coupled plasma mass spectrometry (ICP-MS): Insight into volatility of silicon species in hydrofluoric acid digests for optimal sample preparation and introduction to ICP-MS
A method for the determination of trace levels of silicon from biological materials by inductively coupled plasma mass spectrometry (ICP-MS) has been developed. The volatility of water-soluble silicon species, hexafluorosilicic acid (H2SiF6), and sodium metasilicate (Na2SiO3) was investigated by evaporating respective solutions (50 µg/mL silicon) in nitric acid (HNO3), nitric acid + hydrochloric aAuthorsZikri Arslan, Heather A. LowersPaleoproterozoic reworking of Archean crust and extreme back-arc metamorphism in the enigmatic southern Trans-Hudson orogen
The crustal evolution of the southernmost ∼2000–1800 Ma Trans-Hudson orogen (THO) is enigmatic due to burial by Phanerozoic sediments. We provide new insights through petrochronologic analysis of a paragneiss drill core sample. Detrital zircon age peaks at 2625, 2340, and 1880 Ma and Hf isotopes suggest Paleoproterozoic arc development proximal to Archean source(s). Phase equilibria modeling and tAuthorsIan William Hillenbrand, Amy K. Gilmer, Michael L. Williams, Amanda (Kate) Souders, Michael J. Jercinovic, Heather A. Lowers, Jorge A. VazquezHydrothermal monazite and xenotime chemistry as genetic discriminators for intrusion-related and orogenic gold deposits: Implications for an orogenic origin of the Pogo gold deposit, Alaska
Attempts to geochemically distinguish between metamorphic-hydrothermal systems that form orogenic gold deposits and both reduced and oxidized magmatic-hydrothermal systems using isotopes or metal associations have proven ambiguous, particularly for orogenic gold and reduced intrusion-related gold systems. The absence of conclusive geochemical discriminators and the overlap in geologic characterist
AuthorsRyan Taylor, Garth E. Graham, Heather A. LowersReconnaissance 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 trends dist
AuthorsGarth E. Graham, Erin E. Marsh, Heather A. Lowers, Ryan TaylorThe Mount Weld rare earth element deposit, Western Australia: A carbonatite-derived laterite
Carbonatite-hosted rare earth element (REE) deposits are the primary source of the world’s light REEs and have the potential to be a source of heavy REEs. The Mount Weld REE deposit in Western Australia is hosted in a lateritic sequence that reflects supergene enrichment of the underlying carbonatite complex. Similar to other carbonatite-related ore deposits, ore from Mount Weld displays extreme l
AuthorsPhilip Verplanck, Heather A. Lowers, Adam Boehlke, Jay Michael Thompson, Ganesh Bhat, Cameron Mark MercerHyperspectral cathodoluminescence and quantitative EPMA mapping of angrite northwest Africa 15507
Angrite meteorites represent alkali depleted planetary crust of basaltic composition, and have both plutonic and volcanic lithologies. NWA 15507 is a microgabbroic specimen (mean grainsize ~1.4 mm) composed predominantly of zoned Al-Ti-augite, Ca-bearing olivine and anorthite together with accessory kirschsteinite, rhönite, hercynite, low-Ni kamacite, merrillite, magnetite and troilite. Upon iniAuthorsHeather A. Lowers, Jay Michael Thompson, Paul K. Carpenter, Zoe Wilbur, Anthony IrvingMonazite 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 PaleoproAuthorsIan William Hillenbrand, Michael L. Williams, Karl E. Karlstrom, Amy K. Gilmer, Heather A. Lowers, Michael J. Jercinovic, Kaitlyn Suarez, Amanda (Kate) SoudersCharacterizing 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 tAuthorsJeremy 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. RoseFormation 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 GAuthorsMiguel Tavares Nassif, Thomas Monecke, T. James Reynolds, Yvette D. Kuiper, Richard J. Goldfarb, Sandra Piazolo, Heather A. LowersQuantitative and qualitative correlation of CL and X-ray signals in Cr-bearing jade from Chichén-Itzá Archaeological Zone, Mexico
No abstract available.AuthorsE Vicenzi, Thomas Lam, Heather A. Lowers, Paul K. Carpenter, David T. AdamsCathodoluminescence 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 maAuthorsHeather A. Lowers, Colin MacRae, Nick Wilson, Philip VerplanckThe 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 contAuthorsM. Christopher Jenkins, James E. Mungall, Michael L. Zientek, Kevin Butak, Sam R. Corson, Paul Holick, Ryan McKinley, Heather A. Lowers - News