The anthracites from several coal basins occurring in France, Germany, Ireland, Poland, Romania, Russia, Ukraine and United Kingdom were studied in reflected plane-polarised light (Olympus microscope). Three maceral groups (vitrinite, inertinite, liptinite) and associated mineral matter were distinguished. All the anthracites are dominantly composed of vitrinite (75-95%), inertinite is minor (2.5-19%), and liptinite is very rare (up to 1.5%, with one exception - 4.4%). In vitrinite group, the following macerals: collotelinite, telinite, collodetrinite, vitrodetrinite, and pseudovitrinite were recognised. In inertinite group, the most abundant are fusinite and semifusinite.Liptinite in general is dominated by sporinite. In some anthracites, liptinite was not accounted at all, perhaps, in such highly metamorphosed anthracites, sporinite underwent a rapid change in chemical and physical composition, and became optically indistinguishable from vitrinite. In a few samples, sporinite can be recognised from its vitrinite matrix by a distinct optical morphology. Optical microscopical studies of all anthracites revealed significant heterogeneity of the samples, clearly visible under crossed nicols with the use of higher magnifications. This heterogeneity reflects the differences in coal facies, in primary maceral composition, inherited from peat or sub-bituminous stages but also in strain or pressure being distributed inhomogeneously during formation of anthracite. In all cases, heterogeneous microtexture (fine, coarse, granular, mosaic, and fibrous) was observed. Porous and lamellar particles coexist very often together. Coke-like structure, with numerous devolatilization vacuoles, was also recognised. Pyrolytic carbon occurring as veins, sub-parallel to bedding, can be easily noticed in some samples. Pyrolytic carbon types are presumed to originate from volatiles evolved during condensation reactions.Reflectance values (Rmax) of anthracites vary from 2.3% up to 8.9%. These samples which exhibit Rmax higher than 6% were considered as meta-anthracites. It seems, that the latter are made of conglomerates of graphite-like complexes having preferential planar orientation and structurally less organised compounds with typical turbostratic arrangement of the aromatic units.
Financed by the National Centre for Research and Development under grant No. SP/I/1/77065/10 by the strategic scientific research and experimental development program:
SYNAT - “Interdisciplinary System for Interactive Scientific and Scientific-Technical Information”.