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M. E. Gunter

Publications and source records attributed to M. E. Gunter.

7 recordsLinked to original sources
USGS2009

Mineralogy of mine waste at the Vermont Asbestos Group mine, Belvidere Mountain, Vermont

Samples from the surfaces of waste piles at the Vermont Asbestos Group mine in northern Vermont were studied to determine their mineralogy, particularly the presence and morphology of amphiboles. Analyses included powder X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM), electron probe microanalysis (EPMA), and Raman spectroscopy. Minerals identified by XRD were serpentine-group minerals, magnetite, chlorite, quartz, olivine, pyroxene, and brucite; locally, mica and carbonates were also present. Raman spectroscopy distinguished antigorite and chrysotile, which could not be differentiated using XRD. Long-count, short-range XRD scans of the (110) amphibole peak showed trace amounts of amphibole in most samples. Examination of amphiboles in tailings by optical microscopy, SEM, and EPMA revealed non-fibrous amphiboles compositionally classified as edenite, magnesiohornblende, magnesiokatophorite, and pargasite. No fibrous amphibole was found in the tailings, although fibrous tremolite was identified in a sample of host rock. Knowledge of the mineralogy at the site may lead to better understanding of potential implications for human health and aid in designing a remediation plan.

American Mineralogist↗
USGS2005

Differentiation of commercial vermiculite based on statistical analysis of bulk chemical data: Fingerprinting vermiculite from Libby, Montana U.S.A

Major-, minor-, and trace-element compositions, as determined by X-ray fluorescence (XRF) analysis, were obtained on 34 samples of vermiculite to ascertain whether chemical differences exist to the extent of determining the source of commercial products. The sample set included ores from four deposits, seven commercially available garden products, and insulation from four attics. The trace-element distributions of Ba, Cr, and V can be used to distinguish the Libby vermiculite samples from the garden products. In general, the overall composition of the Libby and South Carolina deposits appeared similar, but differed from the South Africa and China deposits based on simple statistical methods. Cluster analysis provided a good distinction of the four ore types, grouped the four attic samples with the Libby ore, and, with less certainty, grouped the garden samples with the South Africa ore.

American Mineralogist↗
USGS2002

Mineralogical characterization of strata of the Meade Peak phosphatic shale member of the Permian Phosphoria Formation: Channel and individual rock samples of measured section J and their relationship to measured sections A and B, central part of Rasmussen Ridge, Caribou County, Idaho

The Permian Phosphoria Formation of southeastern Idaho hosts one of the largest phosphate deposits in the world. Despite the economic significance of this Formation, the fine-grained nature of the phosphorite has discouraged detailed mineralogical characterization and quantification studies. Recently, selenium and other potentially toxic trace elements in mine wastes have drawn increased attention to this formation, and motivated additional study. This study uses powder X-ray diffraction (XRD), with Rietveld quantification software, to quantify and characterize the mineralogy of composite channel samples and individual samples collected from the stratigraphic sections measured by the U.S. Geological Survey in the Meade Peak Member of the Permian Phosphoria Formation at the Enoch Valley mine on Rasmussen Ridge, approximately 15 miles northeast of Soda Springs, Idaho.

Idaho↗
USGS2002

Mineralogical characterization of weathered and less weathered strata of the Meade Peak phosphatic shale member of the Permian Phosphoria Formation: Measured sections E and F, Rasmussen Ridge, and measured sections G and H, Sage Creek area of the Webster Range, Caribou County, Idaho

The Permian Phosphoria Formation of the western U.S. includes one of the largest phosphate deposits in the world. Despite the economic significance of this formation, its fine-grained nature has discouraged detailed mineralogical characterization and quantitative studies. Recently, selenium and other potentially hazardous trace elements in mine wastes have drawn increased attention to these rocks and motivated more extensive study. Part of this effort has focused on a more detailed geological and mineralogical characterization of the rocks. This study uses powder X-ray diffraction (XRD) with Rietveld quantification software to characterize the mineralogy of channel samples from stratigraphic sections measured by the U.S. Geological Survey in the Meade Peak Phosphatic Shale Member of the Permian Phosphoria Formation. Measured sections are at the Rasmussen Ridge mine and at the Smoky Canyon mine approximately 15 and 25 miles, respectively, northeast of Soda Springs, Idaho. The dominant minerals present in these samples are carbonate-fluorapatite, which is the most common phosphatic ore mineral in this and other marine phosphorites, quartz, muscovite, albite, orthoclase, the ammonium feldspar buddingtonite (NH4AlSi3O8), dolomite, and calcite. Because of their potential for hosting trace elements such as Se, the presence of minor pyrite and sphalerite is also noteworthy. Analysis of the carbonate content in the carbonate-fluorapatite by Rietveld refinement shows relatively low carbonate contents, generally between 2 ? 3% (wt.) CO3 2- in the apatite structure, compared to other marine phosphorites.

Idaho↗
USGS2001

Chemical composition of strata of the Meade Peak Phosphatic Shale Member of the Permian Phosphoria Formation: Channel-composited and individual rock samples of measured section J and their relationship of measured sections A and B, central part of Rasmussen Ridge, Caribou County, Idaho

This study, one in a series, reports bulk chemical composition of rock samples collected from a core, referred to as Measured Section J, drilled at a site that subsequently was developed into the Enoch Valley phosphate mine in southeastern Idaho. The core is continuous and cuts through the entire thickness of the Meade Peak Phosphatic Shale Member of the Phosphoria Formation. The steeply dipping Meade Peak extends from 182 to 495 feet below the ground surface, which is the greatest below-ground depth of rock that has been sampled to date. The core was drilled before the start of mining, and the rocks consequently have not been exposed to the atmosphere or surficial weathering processes or fractured as a result of mining as are the rocks from other described sections. Hence, this section of the Meade Peak in the core is the least altered section of this member sampled in this series of studies. The channel-sampled rocks from Section J form a set of contiguous intervals across the entire thickness of the Meade Peak. These channel samples characterize?in ascending order?the lower phosphate ore, interlayered middle waste shale, upper phosphate ore, and upper waste shale units of the member. The Section J channel-sample suite includes 3 composite samples of the uppermost 7 feet of the Grandeur Tongue of the Permian Park City Formation, a dolomitic unit that directly underlies the Meade Peak. It also includes an analysis of a 0.1 foot section of chert directly overlying the Meade Peak. The concentrations of the chemical elements in the channel samples are compared with those of Measured Sections Aand B that were obtained from the same mine. In addition to the channel samples, 85 rock samples were selected from the core to address specific geochemical questions that resulted from examination of the core. For example, several of these samples correspond to cored rock that had unusual concentrations of various elements that were determined using a hand-held, x-ray fluorescence instrument. Other individual samples consist of several samples taken within a short interval of the core that leads to an abrupt change in lithology. Overall, the rocks from Measured Section J exhibit the least alteration from interaction with ground water compared with rocks from any of the measured sections that have been described in our previous studies.

Idaho↗