Mineralogical and elemental variation of coal from Alberta, Canada: an example from the No. 2 seam, Genesee Mine

Mineralogy and elemental contents were determined on 18 samples from a vert ical profile of the No. 2 seam, Genesee mine, AB. The samples analyzed cons ist of coal, coaly shale, shaly coal, carbonaceous shale, shale, mudstone a nd siltstone. Proximate analysis was determined on all samples. Elemental a nalyses were determined by instrumental neutron activation analysis (INAA) for all elements except As, B, Cd, Hg, Mo, Pb, Se (Atomic Absorption) and B , Ba, Be, Co, Cr, Cu, Li, Mn, Nb, Sr and V (inductively coupled plasma-emis sion spectroscopy, ICP-ES). Samples were low temperature ashed (LTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF) were used to determine quan titative major mineralogy. Accessory mineralogy was determined with Scannin ing Electron microscope/energy dispersive X-ray analyzer (SEM/EDX) on four samples. In general, the coals in the Genesee mine are within the low end o f the range for trace element contents given by Swaine [Swaine, D.J., 1990. Trace Elements in Coal. Butterworths, London, 278 pp.] for most coals. Hig h contents of Cr (9-2620 ppm) and Ni (1-1440 ppm) can be related to an incr eased amount of a Cr-Ni-Fe oxide (chromite-magnetite?) likely derived from ultrabasic diatremes in the Golden-Columbia Icefields, BC area. The No. 2 s eam of the Genesee mine can be divided into two geochemical cycles on the b asis of mineralogy, trace element contents and rare earth element (REE) beh avior. Cycle I consists of quartz, calcite and kaolinite, lower trace eleme nt contents, REE slightly enriched in high rare earth elements (HREE), and thick coal with few partings. Cycle II consists of quartz, calcite, kaolini te, illite, mixed layer and/or expandable lattice clays, feldspar, gypsum, calcium aluminum sulfate hydrate, clinoptilolite, calcite and diopside, hig her trace element contents, REE slightly enriched in light rare earth eleme nts (LREE) and thin coal with a greater frequency of partings. The differen ces between the two geochemical cycles can be accounted for by a decreasing stability of the peat-forming environment resulting from an increasing flu vial influence and volcanogenic input. (C) 2000 Elsevier Science B.V. All r ights reserved.