Denver Microbeam Laboratory

Publications

Filter Total Items: 67
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Year Published: 2019

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...

Egenhoff, Sven; Fishman, Neil; Lowers, Heather A.; Ahlberg, Per

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Year Published: 2019

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...

Meighan, Corey J.; Hofstra, Albert H.; Marsh, Erin E.; Lowers, Heather A.; Koenig, Alan

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Year Published: 2019

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...

Meighan, Corey J.; Hofstra, Albert H.; Adams, David; Marsh, Erin E.; Lowers, Heather A.; Koenig, Alan

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Year Published: 2018

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...

Lowers, Heather A.; Breit, George N.; Strand, Matthew; Pillers, Renee M.; Meeker, Gregory P.; Todorov, Todor I.; Plumlee, Geoffrey S.; Wolf, Ruth E.; Robinson, Maura; Parr, Jane; Miller, Robert J.; Groshong, Steve; Green, Francis; Rose, Cecile
Heather A. Lowers, G. N. Breit, M. Strand, R. M. Pillers, G. P. Meeker, T. I. Todorov, G. S. Plumlee, R. E. Wolf, M. Robinson, J. Parr, R. Miller, S. Groshong, F. Green & C. Rose (2018) Method to characterize inorganic particulates in lung tissue biopsies using field emission scanning electron microscopy, Toxicology Mechanisms and Methods, DOI: 10.1080/15376516.2018.1449042

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Year Published: 2018

Characterizing the source of potentially asbestos-bearing commercial vermiculite insulation using in situ IR spectroscopy

Commercially produced vermiculite insulation from Libby, Montana, contains trace levels of asbestiform amphibole, which is known to cause asbestos-related diseases. When vermiculite insulation is found in a building, evaluation for its potential asbestos content traditionally involves collecting a sample from an attic or wall and submitting it for...

Swayze, Gregg A.; Lowers, Heather A.; Benzel, William M.; Clark, Roger N.; Driscoll, Rhonda L.; Perlman, Zac S.; Hoefen, Todd M.; Dyar, M. Darby

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Year Published: 2017

Geochemistry and mineralogy of the Dotson Zone HREE deposit in the Bokan Mountain peralkaline igneous complex, southeastern Alaska, USA

The Bokan Mountain igneous complex (BMIC) is a typical example of a peralkaline intrusive system that has evolved to the point of developing late stage HFSE- and REE-rich silicic pegmatites and dikes. The Dotson Zone comprises a series of felsic dikes that extend from the southeast margin of the composite pluton and may represent an important...

Taylor, Cliff D.; Lowers, Heather A.; Adams, David; Robinson, R. James
Taylor, C.D., Lowers, H.A., Adams, D.T., and Robinson, R.J., 2017, Geochemistry and mineralogy of the Dotson Zone HREE deposit in the Bokan Mountain peralkaline igneous complex, southeastern Alaska, USA. Proceedings of the 14th SGA Biennial Meeting, 20-23 August 2017, Quebec City, Canada, p. 1329-1332.

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Year Published: 2017

USGS Spectral Library Version 7

We have assembled a library of spectra measured with laboratory, field, and airborne spectrometers. The instruments used cover wavelengths from the ultraviolet to the far infrared (0.2 to 200 microns [μm]). Laboratory samples of specific minerals, plants, chemical compounds, and manmade materials were measured. In many cases, samples were purified...

Kokaly, Raymond F.; Clark, Roger N.; Swayze, Gregg A.; Livo, K. Eric; Hoefen, Todd M.; Pearson, Neil C.; Wise, Richard A.; Benzel, William M.; Lowers, Heather A.; Driscoll, Rhonda L.; Klein, Anna J.
Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035.

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Year Published: 2016

The distribution and composition of REE-bearing minerals in placers of the Atlantic and Gulf coastal plains, USA

Rare earth element (REE) resources are currently of great interest because of their importance as raw materials for high-technology manufacturing. The REE-phosphates monazite (light REE enriched) and xenotime (heavy REE enriched) resist weathering and can accumulate in placer deposits as part of the heavy mineral assemblage. The Atlantic and Gulf...

Bern, Carleton R.; Shah, Anjana K.; Benzel, William M.; Lowers, Heather A.
Bern, C.R., Shah, A.K., Benzel, W.M., Lowers, H.A. 2016. The distribution and composition of REE-bearing minerals in placers of the Atlantic and Gulf coastal plains, USA. Journal of Geochemical Exploration, doi:10.1016/j.gexplo.2015.12.011

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Year Published: 2016

Ore mineralogy and textural zonation in the world-class epithermal Waihi Vein System, Hauraki Goldfield

The Waihi district in the Hauraki Goldfield of New Zealand contains adularia-sericite epithermal gold-silver veins that have produced more than 7.7 Moz gold. The outermost veins of the district (Martha, Favona, Moonlight, and Cowshed) contain abundant colloform, cherty, and black quartz fill textures, with minor crustiform and massive quartz. The...

Mauk, Jeffrey L.; Skinner, Erin G; Fyfe, Sarah J; Menzies, Andrew H; Lowers, Heather A.; Koenig, Alan E.
Mauk, J.L., Skinner, E.G., Fyfe, S.J., Menzies, A.H., Lowers, H., and Koenig, A., 2016, Ore mineralogy and textural zonation in the world-class epithermal Waihi vein system, New Zealand: in Christie, A.B., ed., AusIMM Monograph 31: Mineral Deposits of New Zealand—Exploration and Research, p. 293-301.

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Year Published: 2015

Petrology and diagenetic history of the upper shale member of the Late Devonian-Early Mississippian Bakken Formation, Williston Basin, North Dakota

The organic-rich upper shale member of the upper Devonian–lower Mississippian Bakken Formation (Williston Basin, North Dakota, USA) has undergone significant diagenetic alteration, irrespective of catagenesis related to hydrocarbon generation. Alteration includes precipitation of numerous cements, replacement of both detrital and authigenic...

Neil S. Fishman; Sven O. Egenhoff; Boehlke, Adam; Lowers, Heather A.
Fishman, N.S., Egenhoff, S.O., Boehlke, A., and Lowers, H.A., 2015, Petrology and diagenetic history of the upper shale member of the Late Devonian-Early Mississippian Bakken Formation, Williston Basin, North Dakota in Larsen, D., Egenhoff, S.O., Fishman, N.S., ed., Paying Attention to Mudrocks: Priceless!: Geological Society of America Special Papers, Vol. 515, p. 125-151. Available at: http://dx.doi.org/10.1130/2015.2515(07)

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Year Published: 2015

Mining for metals in society's waste

Metals are crucial to society and enable our modern standard of living. Look around and you can't help but see products made of metals. For instance, a typical gasoline-powered automobile contains over a ton of iron and steel, 240 pounds of aluminum, 42 pounds of copper, 41 pounds of silicon, 22 pounds of zinc and more than 30 other mineral...

Smith, Kathleen S.; Plumlee, Geoffrey S.; Hageman, Philip L.
Smith, K.S., Hageman, P.L., and Plumlee, G.S., 2015, Mining for metals in society's wastes: The Conversation US, October 1, 2015, https://theconversation.com/mining-for-metals-in-societys-waste-43766.

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Year Published: 2015

Lithostratigraphic, borehole-geophysical, hydrogeologic, and hydrochemical data from the East Bay Plain, Alameda County, California

The U.S. Geological Survey, in cooperation with the East Bay Municipal Utility District, carried out an investigation of aquifer-system deformation associated with groundwater-level changes at the Bayside Groundwater Project near the modern San Francisco Bay shore in San Lorenzo, California. As a part of the Bayside Groundwater Project, East Bay...

Sneed, Michelle; Orlando, Patricia v.P.; Borchers, James W.; Everett, Rhett R.; Solt, Michael; McGann, Mary; Lowers, Heather; Mahan, Shannon
Sneed, Michelle, Orlando, P.v.P., Borchers, J.W., Everett, Rhett, Solt, Mike, McGann, Mary, Lowers, Heather, and Mahan, Shannon, 2015, Lithostratigraphic, borehole-geophysical, hydrogeologic, and hydrochemical data from the East Bay Plain, Alameda County, California: U.S. Geological Survey Data Series 890, 56 p., http://dx.doi.org/10.3133/ds890.