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C. B. Cecil

Publications and source records attributed to C. B. Cecil.

26 records · Page 2Linked to original sources
USGS1984

MICROCHARACTERIZATION OF ARSENIC- AND SELENIUM-BEARING PYRITE IN UPPER FREEPORT COAL, INDIANA COUNTY, PENNSYLVANIA.

Optical and scanning electron microscope as well as electron and proton microprobe techniques have been used in a detailed investigation of the modes of occurrence of arsenic and selenium in pyrite in Upper Freeport coal from the Homer City area, Indiana County, Pennsylvania. Polished blocks were prepared from columnar samples of the coal bed to represent particular zones continuously from top to bottom. Initial selection of zones to be studied was based on chemical analysis of bench-channel samples. Microprobe data indicate that the highest concentrations of arsenic (as great as 1. 5 wt. %) are apparently in solid solution in pyrite within a limited stratigraphic interval of the coal bed. Smaller amounts of arsenic and selenium (concentrations up to approximately 0. 1 and 0. 2 wt. % respectively) were detected at isolated points within pyrite grains in various strata of the coal bed.

Scanning Electron Microscopy↗
USGS1983

RECENT DEVELOPMENTS ON THE ORIGIN OF MINERAL MATTER IN COAL.

This study attempts to quantify some of the various origins of mineral matter. Data developed for the Upper Freeport coal bed indicates that mineral matter other than pyrite and calcite is primarily derived from the vegetal matter that ultimately became coal. Cathodoluminesence was used to verify that the quartz in the Upper Freeport coal is dominantly authigenic and not detrital in origin. Sulfur variability in coal beds of the central Appalachian Basin was investigated stratagraphically.

Conference Paper↗
USGS1982

Geologic factors that control mineral matter in coal

Elements other than organically derived and bound C, H, N, O, and S constitute mineral matter in coal. Mineral matter may consist of discrete minerals such as calcite, quartz, clays, and pyrite, and/or organic compounds that contain organically bonded elements such as Ca and CI. Processes that may affect the association and content of mineral matter are operable from the initial peat-forming stage to the time of utilization of the coal. However, the objective of this paper is to discuss some of the various geologic processes that may influence content and associations in unmined coal.

Book chapter↗
USGS1982

The 57 Fe Mössbauer parameters of pyrite and marcasite with different provenances

Eighteen pyrite and twelve marcasite samples which have different provenances have been investigated to determine the systematics of the influence of mineralogical and geological factors on the 57 Fe Mössbauer spectra at 298 K. The following results have been obtained: there is no ambiguity in distinguishing single phase pyrite from single phase marcasite by means of 57 Fe Mössbauer spectroscopy at 298 K. At 298 K the average electric quadrupole splitting, 〈 ΔE Q 〉, and average isomer shift, 〈δ〉, with respect to Fe metal, are 0.6110 ± 0.0030 mm s −1 and 0.313 ± 0.008 mm s −1 , respectively, for the 18 pyrites; 〈 ΔE Q 〉 = 0.5030 ± 0.0070 mm s −1 and 〈 δ 〉 = 0.2770 ± 0.0020 mm s −1 for the 12 marcasites. At 77 K, ΔE Q is 0.624 mm s −1 for pyrite and 0.508 mm s −1 for marcasite. In distinguishing pyrites from marcasites, spectra obtained at 77 K are not warranted. The Mössbauer parameters of pyrite and marcasite exhibit appreciable variations, which bear no simple relationship to the geological environment in which they occur but appear to be selectively influenced by impurities, especially arsenic, in the pyrite lattice. Quantitative and qualitative determinations of pyrite/marcasite mechanical mixtures are straightforward at 298 K and 77 K but do require least-squares computer fittings and are limited to accuracies ranging from ±5 to ±15 per cent by uncertainties in the parameter values of the pure phases. The methodology and results of this investigation are directly applicable to coals for which the presence and relative amounts of pyrite and marcasite could be of considerable genetic significance.

Geochimica et Cosmochimica Acta↗