Submicron-scale mineralogy of lithotypes and the implications for trace element associations: Blue Gem coal, Knox County, Kentucky

Journal Article · Mon Apr 16 00:00:00 EDT 2018 · International Journal of Coal Geology

DOI:https://doi.org/10.1016/J.COAL.2018.04.006· OSTI ID:1434657

Hower, James C. ^[1]; Berti, Debora ^[2]; Hochella, Michael F. ^[3]; Rimmer, Susan M. ^[4]; Taulbee, Darrell N. ^[1]

---

1. Univ. of Kentucky, Lexington, KY (United States). Center for Applied Energy Research
2. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). National Center for Earth and Environmental Nanotechnology Infrastructure (NanoEarth)
3. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Geosciences; Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Subsurface Science and Technology Group and Energy and Environment Directorate
4. Southern Illinois Univ., Carbondale, IL (United States). Dept. of Geology

Transmission electron microscopy accompanied by energy-dispersive spectroscopy and selected area electron diffraction of density-gradient separates from two lithotypes of the low-ash, low-sulfur Blue Gem coal, eastern Kentucky, revealed an array of previously unrecognized (in this coal, and arguable in most others) sub-micron minerals, some <10 nm in size. The first sample representing the 1.22–1.24 specific gravity fraction of the middle bench contains a mineral identified as a La-, Ce-, Nd-bearing monazite; other minerals with CrFe, CuFeS, FeZn-S, and Pb; and areas, probably comprising agglomerates of several grains, if not several minerals, with concentrations of Mg, Ca, Ti, Fe, Zn, Zr, and Mo. The second sample representing the 1.30–1.31 specific gravity fraction of the basal lithotype has aggregates of particles enriched in Mg, Ca, Ti, and Fe. Individual grains not specifically quantified include CrNiMnCuFeS, AgS, and CuS. Detailed investigation of one area (most of the variation within a <4 μm² region) demonstrates the presence of greenockite (CdS); minute phases containing NiCoGe and AgCdBi, the latter with a more evident S association than the former; metallic Bi; nisnite (Ni₃Sn); silver cadmium; manganosite (MnO); and siderite. Some minerals, such as the monazite, are most likely of detrital or tuffaceous origin. Many of the other assemblages could be of hydrothermal origin, a hypothesis supported by known regional geochemical and coal rank trends, but not previously demonstrated in mineral assemblages at the 10's of nm scale in this region.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE; National Nanotechnology Coordinated Infrastructure (NNCI); Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). National Center for Earth and Environmental Nanotechnology Infrastructure (NanoEarth); National Science Foundation (NSF); Univ. of Kentucky, Lexington, KY (United States)
• Grant/Contract Number: ECCS 1542100; CBET-1510861; AC05-76RL01830
• OSTI ID: 1434657
• Journal Information: International Journal of Coal Geology, Vol. 192; ISSN 0166-5162
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
58 GEOSCIENCES
Rare earth elements
Transmission electron microscopy
Low-ash coal
Silver
Cadmium