QUANTITATIVE COAL MINERALOGY OF THE SYDNEY COALFIELD, NOVA-SCOTIA, CANADA, BY SCANNING ELECTRON-MICROSCOPY, COMPUTERIZED IMAGE-ANALYSIS, AND ENERGY-DISPERSIVE X-RAY SPECTROMETRY

Automated image and X-ray analysis, with a scanning electron microscope, has been used to "fingerprint' mineral particles in bituminous coals of the Sydney Coalfield and catalogue their chemical class and size distribution. Four seams (Hub, Harbour, Phalen, and Gardiner) were analyzed quantitatively for some 32 000 mineral particles; these analyses revealed particle-size and weight distributions for 27 chemical classes. Manual searches augmented the computer-automated scans, covering eight seams and recording a total of 35 mineral species, their paragenesis, and sites for 28 elements. Sydney seam mineralogy is dominated by pyrite and kaolinite, but illite, chlorite, siderite, ankerite, and quartz are locally prominent; these are accompanied by a large variety of accessory minerals (zircon, rutile, apatite, barite, gypsum, rare-earth phosphates, and ore minerals) and alteration products (goethite and hydrated sulphates). Individual column benches show geochemical facies with different mineral suites resulting from cyclic sedimentation, hydrologic conditions, and changes in pore-water chemistry during peat accumulation, coalification, and diagenesis. -from Author