Vitrain Bands Research Articles

Critical insights from Rock-Eval analysis of vitrains

Rock-Eval S2 and S4 curves are commonly used to interpret active source rocks. In this work we report the formation of unusual, uneven, spiky S2 pyrograms from Rock-Eval of manually isolated vitrain bands from Mvb and Lvb coals. The spikes and unevenness in the S2 curves for coking-vitrains are interpreted to form from the release of gases or bubbles bursting from the melt during the pyrolysis stage. Crucible swelling numbers measured for these vitrains were observed to be 3 to 4 times higher than the parent coal from which they were separated. Field Emission Scanning Electron Microscope (FE-SEM) images also document formation of three dimensional bubbles due to bursting of gaseous bubbles, in the pyrolysis-residue (using Rock-Eval) of coking-vitrains. For bulk coal samples and vitrains isolated from HvbA coals, the S2 pyrograms were observed to be smooth. At higher sample weights, the formation of spikes for the vitrains from Mvb and Lvb was observed to increase, irrespective of the heating-rates used, owing to the release of greater amounts of gases or bubbles bursting from the melt. The results indicate the importance of cross-examining S2 pyrograms as it offers clues towards the behavior of coals during pyrolysis, and for better interpretation of results.

Abundance and distribution pattern of rare earth elements and yttrium in vitrain band of high-rank coal from the Qinshui basin, northern China

Vitrain bands are clean and contain less ash than the bulk coal. A comprehensive study on rare earth elements and yttrium (REY) in vitrain may provide insights into the REY affinity. In this study, abundance and distribution pattern of REY in bulk coal, vitrain band and HCl-HF demineralized vitrain band was investigated. The coal studied in the present work was low-ash (ash yields ranging from 4.13 to12.86%, with 8.59% as the average), high-rank (anthracite to semi-anthracite, with volatile matter yields of 7.52–13.42%, 9.58% on average) coal of Permian Shanxi Formation, collected from the Sihe and Zhaozhuang mines, southern Qinshui Basin. The major minerals identified by powder XRD are illite and kaolinite, with small amount of ankerite, chlorite, calcite, siderite and pyrite. In comparison to the bulk coal, vitrain band displays a lower REY content and smaller compositional range. The bulk coal has N-, H- and L-type REY patterns based on Seredin-Dai’s classification, while the REY distribution for the vitrain band is commonly characterized by an H-type pattern. Moreover, the LaN/LuN ratio in the vitrain band is usually lower than that in the bulk coal. This probably suggests that the organic component has a higher HREY association than LREY compared to the inorganic part. The limited impact of HCl-HF demineralization on content and distribution pattern of REY in vitrain band probably reflects the weak acid solubility of REY in the vitrain band. The sequential chemical extraction procedure reveals that the clays and the residual organics, which have a stronger association with LREY and HREY respectively, are the dominant carriers of total REY in the studied bulk coals.

CanWe Identify Macroscopic Texture of Coal under Microscopic Analysis Using Standard Petrographic Method?

Macroscopic texture in coals is not much getting attention to identify, becauseit is believed it doesn’t hold much information about the coal characteristics. It is nottrue because some of important coal characteristics lie in its organic content which is reflected in its macroscopic texture (Moore, 2016). Conventional petrographic method using crushed sample cannot distinguish such feature microscopically, since the macroscopic texture will lose its integrity during the preparation. Petrographic analysis using block samples provide information about microscopic texture that can represents its macroscopic texture. Components in textural analysis are divided into three types based on the size, band (more than 800 μm), lens (20–800 μm) and matrix (less than 20 μm). From the ratio between these three types of component and statistics, later it can be determined that nonbandedsamples have less value of ratio between band and lens per matrix, and there will be a borderline between banded and non-banded samples based on the value. Banded texture in macroscopic feature consists of vitrain bands, and under microscope it can beidentified as band and lens of macerals, while non-banded samples will mostly consist ofmatrix texture. Thus, it can be concluded that petrographic analysis using block samplescan be used to identify microscopic texture representing the macroscopic texture, and can be proven through statistics as used in this research.

Stratified Sampling to Define Levels of Petrographic Variation in Coal Beds: Examples from Indonesia and New Zealand

DOI: 10.17014/ijog.3.1.29-51Stratified sampling of coal seams for petrographic analysis using block samples is a viable alternative to standard methods of channel sampling and particulate pellet mounts. Although petrographic analysis of particulate pellets is employed widely, it is both time consuming and does not allow variation within sampling units to be assessed - an important measure in any study whether it be for paleoenvironmental reconstruction or in obtaining estimates of industrial attributes. Also, samples taken as intact blocks provide additional information, such as texture and botanical affinity that cannot be gained using particulate pellets. Stratified sampling can be employed both on ‘fine’ and ‘coarse’ grained coal units. Fine-grained coals are defined as those coal intervals that do not contain vitrain bands greater than approximately 1 mm in thickness (as measured perpendicular to bedding). In fine-grained coal seams, a reasonable sized block sample (with a polished surface area of ~3 cm2) can be taken that encapsulates the macroscopic variability. However, for coarse-grained coals (vitrain bands >1 mm) a different system has to be employed in order to accurately account for the larger particles. Macroscopic point counting of vitrain bands can accurately account for those particles>1 mm within a coal interval. This point counting method is conducted using something as simple as string on a coal face with marked intervals greater than the largest particle expected to be encountered (although new technologies are being developed to capture this type of information digitally). Comparative analyses of particulate pellets and blocks on the same interval show less than 6% variation between the two sample types when blocks are recalculated to include macroscopic counts of vitrain. Therefore even in coarse-grained coals, stratified sampling can be used effectively and representatively.

The influence of macroscopic texture on biogenically-derived coalbed methane, Huntly coalfield, New Zealand

Secondary biogenic gas content can be related to textural characteristics in Eocene age subbituminous coals from the Huntly coalfield, New Zealand. However, the relationships between the two major coal seams in the basin are considerably different despite their close stratigraphic proximity (less than 25 m). In this study, 163 coal samples were collected and desorbed from eight drill holes. Gas adsorption capacity and proximate analyses were conducted as well as macroscopic logging for coal type and vitrain banding characteristics. Vitrain bands were quantitatively point counted and the longest dimension of the shortest axis measured. Three coal types were recognized: bright luster non-banded, bright moderately banded and bright highly banded. Vitrain band thickness, converted to the phi (− log2) scale, was found to increase across the coal types with the thickest bands being associated with the most banded coal type. Overall, when normalized by seam and location, the dataset reveals a relationship between coal type and gas content with the non-banded coal type having the highest gas contents and conversely, the coal types with the most vitrain bands having the lowest gas contents. However, when the seams are considered separately, it can be seen that in the stratigraphically higher Renown coal seam, gas has an indirect association with increasing band thickness, in agreement with the overall trend, while the stratigraphically lower Kupakupa coal seam appears to have a direct relationship. Interestingly the Renown seam, which has a greater percentage of non-banded material, generally has a greater methane adsorption capacity as well as a greater gas content compared to the Kupakupa seam. It is believed these differences are related to macroscopic texture and that the differing proportions of the coal types between the two seams has a fundamental effect on microporosity, ultimately controlling the available surface area for gas adsorption.

Surface properties of photo-oxidized bituminous vitrains

The principal aim of this research was to determine whether correlations could be established among surface oxygen functionality, hydrophobicity induced by photo-oxidation, and measurements of fluorescence alteration. Polished surfaces of vitrain bands were photo-oxidized using a blue-light flux and then changes in surface properties were measured. The data obtained reveal significant variations depending upon the level of surface oxidation. There is a progressive and significant increase in the amount of near-surface oxygen concentration which appear to lower the hydrophobicity as shown by contact angle measurements. Although this influence diminished as coal rank increased, the level of oxygen uptake was about the same, suggesting that the type of oxygen functionality formed during oxidation may be of great importance in modifying surface hydrophobicity. Changes in functional-group chemistry showed a general increase in the concentration of carbonyl-containing groups while those of CH 2 groups decreased. All of these observations follow the trends observed in previous investigations of naturally weathered coals. The photo-oxidation technique also resulted in the development of phenolic, ester and anhydride moieties instead of the expected emplacement of carboxylic acid groups which are normally associated with naturally weathered coals. Increase in the concentration of esters and anhydrides would be expected to result in a more hydrophobic surface, the opposite of what was actually encountered.

Coal deposition in the Noric Depression (Eastern Alps): raised and low-lying mires in Miocene pull-apart basins

Pull-apart basins often form during the late stage of continental collision. Provided appropriate climatic conditions, these basins may contain thick coal seams. Two such examples are the Leoben and Fohnsdorf Basins in Austria, which formed in Miocene times during the post-collisional stage of the Alpine orogene. Both basins contain more than 10 m of sub-bituminous coal. Despite similar ages, tectonic settings, and similar stratigraphic position of the seams within the sedimentary sequence, the properties of the coals differ significantly. The Leoben coal is quite clean, whereas Fohnsdorf coal is rich in ash and sulfur. Petrographical and geochemical methods were applied to reconstruct the environmental factors that controlled coal properties in these basins. Coal formation in the Leoben Basin commenced in an eutrophic, low-lying mire. This was followed by deposition of the main body of coal, which formed in an ombrotrophic raised mire. Coal deposition was only shortly interrupted by deposition of volcanic ashes. Due to an acid paleo-environment, the volcanic material within the raised mire was altered to kaolinite. Thick vitrain bands representing large trees are found in the lower part of the seam only. Siderite is the main inorganic constituent in the main coal body. Lakes within the raised mire were present during late stages of peat accumulation and were filled with sapropelic coal. The high ash yields of this facies are due to abundant siliceous sponges, siliceous crusts, and tuffogenic minerals. Finally, high subsidence rates caused the flooding of the raised mire and sapropelic shales were deposited in the newly formed lake. The iron, which formed siderite in the raised mire, and biogenic and abiogenic silica present in the lakes within the raised mire, are derived from volcanic ashes. The high-ash Fohnsdorf coal was formed in a low-lying mire close to a brackish lake. The seam geometry is controlled by the progradation of a fluvio-deltaic system into the brackish lake, and its subsequent drowning. The roof of the seam is formed by coquinoidal limestones and sapropelic shales. The brackish influence reduced the acidity of the mire, which resulted in the transformation of volcanic glass into montmorillonite. The low acidity also promoted high bacterial activity, which together with the high sulfate content of brackish waters, explains the high sulfur and pyrite content of the coal. Its high content of biogenic (?) methane is probably another effect of bacterial activity. Low-ash, low-sulfur coal is restricted to thin layers. These might represent local raised mires, which formed after the withdrawal of a fluvial system.

99/00090 Surface studies of low-temperature oxidation of bituminous coal vitrain bands using XPS and SIMS

99/00090 Surface studies of low-temperature oxidation of bituminous coal vitrain bands using XPS and SIMS

Surface studies of low-temperature oxidation of bituminous coal vitrain bands using XPS and SIMS

Surface oxidation of samples from vitrain bands (low mineral content) in two Australian bituminous coals (Greta and Whybrow seams, Sydney Basin, NSW) were studied following thermal treatment in air at temperatures ranging from 20°C to 120°C for periods of up to 370 days. X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) studies indicate clear changes in oxygen function group concentration at the surface of coal organic matter under different atmospheric oxidation conditions. The oxidation products observed include hydroxyl groups or ether linkages, carbonyl groups, and carboxyl groups. Increases in oxidation temperature accelerate the process of carboxyl group formation. It is found that the surface concentration of carboxyl groups can be used as an indicator of the extent of oxidation in low sulfur-content bituminous coals. This may be useful in coal preparation research.

98/00161 Structural characterization of oils generated by the Gray-King pyrolysis of vitrains and oil/vitrain relation

DTA, modified DTA, thermogravimetric and spectrochemical analyses were performed on twelve samples of Carboniferous carbonaceous shales and coals and two samples of vitrain (separated from the carbonaceous shale or coal) in west-central Sinai. The analyses indicate that these coals and carbonaceous shales belong to the high-volatile sub-bituminous A coal-rank.Trace-element contents for Pb, Zn, Ga, B, Mn, Ge, Ni, V, Cr, Cu and U are given and averaged. These are then compared with the averages for the only published trace-element contents of the nearby Jurassic Ayun Musa coals. They are found to be richer in Pb, Zn and Ga. Ge is remarkably concentrated in the vitrain bands and seamlets inside the Carboniferous Sinai host-coals while V, Zn and Pb and, to a lesser extent, Mn, Cr and U are depleted in vitrains relative to their host-rocks.

97/02513 The influence of photo-oxidation on the wettability of vitrinite from bituminous rank coals

Luminescence photometric techniques were employed to alter the surface chemistry of vitrinite from bituminous coals in order to determine the effects of surface oxidation on coal wettability and flotation. Blocks and powdered concentrates of vitrain were prepared from three coals of hvCb, hvAb and mvb ranks. Blocks containing vitrain bands were photo-oxidized under blue light (390--490 nm) for various time intervals and examined for specific changes in luminescence intensity, surface chemistry and wettability. Particulate samples were irradiated under ultraviolet light ({approx}366 nm) and then tested for changes in flotation. Analytical results from reflectance-mode FTIR show that blue-light irradiation of the vitrinite surfaces results in a photo-oxidation that increases aromatic carbonyl and hydroxyl groups and decreases methyl group concentration with irradiation time. Contact angle measurements on fresh and photo-oxidized vitrains show that surface wettability increases with irradiation time; the magnitude of this change decreases with increasing coal rank. Preliminary film flotation results show that increasing levels of surface oxidation diminishes flotation yields.

Geochemistry and petrography of the Taupiri and Kupakupa coal seams, Waikato coal measures (Eocene), New Zealand

Geochemical and conventional petrographic techniques have been used to characterise variation within and between the Eocene Taupiri and Kupakupa coal seams in New Zealand. Both seams have a macroscopically bright lustre, but the Taupiri is dominated by non-banded coal in contrast to portions of the Kupakupa which contain large (1–3 cm thick) vitrain bands. Microscopically these bands contribute the bulk of the humotelinite (preserved tissue) found in both coals. The Kupakupa seam contains higher proportions (approx. 20%) of humotelinite than the Taupiri (approx. 10%) which contains higher concentrations of liptinite and sclerotinite. Both seams show a general decrease in humotelinite upwards in the seam, although inorganic partings can modify that general trend, especially in the Kupakupa. In all three splits of the Taupiri, eugelinite decreases upwards whilst detrogelinite proportions increase. These petrographic attributes suggest that the Taupiri palaeo-peat was subjected to higher levels of degradation than the Kupakupa. Coal geochemistry, when interpreted in the context of seam geometry and stratigraphic relationships, reveals a complex chemical history. Major element analyses supplemented by mineralogical analyses confirm previous work indicating a strong organic association for Ca, Mg, Na, Fe and B. These elements are more abundant in seams which are overlain by other coal seams, indicating depletion by circulation of groundwater of surface origin. For example, Na values in a split Taupiri seam at Maori Farm #3 Opencast vary across major sediment partings, being highest in the lowermost coal interval. Si/Al ratios vary widely, and commonly fall below the composition of kaolinite, indicating breakdown of silicates and transport of silica and alumina in solution at the time of peat accumulation. Ti and P in whole coal fluctuate substantially, and their present distribution also indicates mobility in solution. There appears to be little association between elemental and maceral variation. However, there is a clear association in the Kupakupa coal seam at the Weavers Opencast between P, presence of organic partings and the degree of vitrain banding. The highest concentrations of P are within and just below inorganic partings; similarly, the highest abundance of vitrain bands occur just above and/or below partings. Although probably not causally related, the increase in P and vitrain band abundance may be related to the same process; that is, flooding of the Kupakupa palaeo-mire with sediment-laden waters. A quicker burial from sediment loading and less aerobic degradation may have preserved the plant root material (vitrain bands). The P may have resulted either from the flood waters themselves or as residual P in buried plant material. In either case, immobilisation in insoluble form by reaction with Al species is probable.

Delineation of the distinctive nature of tertiary coal beds

Floral character in mires has changed progressively through time. In the Carboniferous, pteridophytes, sphenophytes and lycophytes were dominant but by the Permian gymnosperms were an important component of mire flora. During the early Mesozoic gymnosperms remained the characteristic mire vegetation, together with pteridophytes, and conifers became dominant during the Jurassic. Cretaceous and Paleocene vegetation are similar, with taxodiaceous flora being important in mire vegetation. From the Eocene onwards, however, angiosperms were increasingly dominant in mire communities and in the Miocene herbaceous vegetation began to play a significant role. Together with these changes in floral character at least three aspects of coal character also appear to vary sequentially with time and are distinctive in the Tertiary: (1) proportions and thickness of vitrain banding, (2) coal bed thickness and (3) proportions of carbonised material. A compilation has been made of data from the coal literature comparing older coals with those of the Tertiary, in order to give a perspective in which to examine Tertiary coals. It was found that only Tertiary coals contain significant proportions of coal devoid of vitrain bands. In addition, Tertiary coals are the thickest recorded coal beds and generally contain low percentages of carbonised material (many less than 5%) as compared to older coals. It is interesting to note that Paleocene coal beds are similar to Cretaceous coals in that they tend to be thinner and contain higher proportions of carbonised material than do younger Tertiary coals. The absence of vitrain bands in some Tertiary coal beds is thought to result from the floras dominated by angiosperms, which are relatively easily degraded as compared to gymnosperms. The thickness of Tertiary coals may be related to an increase in biomass production from the Carboniferous through to the Tertiary, as plants made less investment in producing lignin, an energy-intensive process. In addition, with less lignin in plants, easier degradation of biomass may have facilitated nutrient recycling which, in turn, led to greater biomass production. Increased biomass production may have also ‘diluted’ the carbonised material present in some Tertiary peats, leading to lower proportions in the coal. Another possible cause of decreased carbonised components in Tertiary coal is that decreasing lignin content resulted in decreased charring during fires, as lignin is particularly prone to charring. A third possibility is that the carbonised component of peat may be concentrated during coalification so that Tertiary coals, generally of lower rank than Mesozoic or Paleozoic coals, contain a smaller fraction of carbonised plant material. It is not at present clear which of these mechanisms may have affected carbonised material in peat and coal but it is clear that lignin type and content has had an important role in determining peat and coal character since the Paleozoic.

Floral assemblage of the “D” coal seam (Cretaceous): Implications for banding characteristics in New Zealand coal seams

Abstract Two complete vertical sections were studied from the uppermost Cretaceous “D” coal seam near Greymouth, New Zealand. The thickest and most concentrated vitrain bands occur in the paleomire centre and bands are thinner and less abundant at the paleomire margin. Botanical analysis of the vitrain bands indicates they formed entirely from the secondary xylem (wood) of gymnosperms. Palynomorphs indicate that there is no consistent correlation between conifer pollen abundance and the degree of vitrain banding. However, maximum preservation of vitrain bands coincides with an inferred transition from a rheotrophic mire (as indicated by Phyllocladidites mawsonii pollen) to an acidic and possibly ombrotrophic system (as indicated by the abundance of Gleicheniaceae spores). This suggests that the presence/absence of gymnosperm secondary xylem as vitrain bands is controlled at least in part by mire chemistry.

Structural characterization of the organic polymers comprising a lignite's matrix and megafossils

The geochemical and petrographic character of the matrix of the Oligocene, angiospermous Brandon lignite, Vermont, is examined and compared to samples of a common fossilized angiosperm wood and fruit endocarp contained within the lignite. The lignite matrix is composed primarily of humodetrinite and liptodetrinite while the megafossils are overwhelmingly humotelinitic (textinite and ulminite). Curie-point Py-MS, in-source Py-EI-MS, in-source Py-CI-MS, and CPMAS 13C NMR reveal that the polymers comprising the matrix include a highly aliphatic polymer(s) and polymer(s) derived from the significantly modified remains of angiosperm lignin(s). Very few polysaccharides are preserved in the matrix. The polymer(s) in each megafossil contain(s) significant proportions of polysaccharides and lignins which are, however, significantly altered from their Recent equivalents. The results suggest that anatomical preservation and physical integrity of discrete megafossils within peats and lignites are directly related to the degree to which the original ligno-cellulosic framework is preserved. This implies that the humotelinitic macerals comprising the megafossils contain ligno-cellulose-derived polymers that are less modified than those comprising the humodetrinite within the matrix. The liptodetrinite within the matrix is probably comprised of highly aliphatic polymers derived from cutans and/or alginans. Upon further coalification the vitrinite within the vitrain bands derived from the megafossils and vitrinite within the clarain bands derived from the matrix would be distinct.

A test for the analogy of tropical domed peat deposits to “dulling up” sequences in coal beds—Preliminary results

Megascopic and microscopic characteristics of a domed peat deposit in Sarawak, Malaysia were examined to test their analogy to “dulling up” sequences in low-ash coal beds. Preliminary petrographic results show high concentrations (> 95%) of vitrinite precursor material for all peat types, but that fibrous peats in the upper central portion of the deposit contain more preserved plant material than peats toward the base and margins which, although more decomposed, contain large fragments (5–150 cm) of wood. These results present contradictory evidence in support of a dulling up model and suggests that modern tropical peat domes are perhaps poor petrographic analogues for dulling up sequences. This deposit would produce an “all bright” coal seam with bright vitrain bands of variable thickness and amount, set in bright, high vitrinite matrix.

Comparative geochemistry of vitrinite kerogens from Carboniferous and Tertiary provinces

In this study, vitrinite concentrations were prepared from vitrain bands from two Carboniferous coal seam locations in Eastern United States, a Tertiary age coal seam in Alaska and a Tertiary age coal seam in Western Canada. These vitrinite samples were characterized using pyrolysis-gas chromatography in addition to petrographic and bulk chemical analyses. The purpose of this study is to apply quantitative pyrolysis-gas chromatography to a set of vitrinite concentrates from different coal basins of different age which are at relatively similar levels of rank and determine whether compositional variation can be observed.

Petrographic Characterization of Coals in Kozlu and Kilic Formations (Westphalian A), Zonguldak, Turkey: ABSTRACT

The Zonguldak coal region is about 130 km (80 mi) long and 30-50 km (18-31 mi) wide and is situated on the southwest coast of the Black Sea. The basin is the main bituminous coal-producing region of Turkey. It has a complicated faulted structure. The Carboniferous of the Zonguldak region consists of three natural divisions: Alacaagzi (Namurian), Kozlu and Kilic (Westphalian A), and Karadon (Westphalian B, C, and D). The main concern of this study is the Kozlu and Kilic Formations, which have about 31 coal seams with a total thickness of 45 m (150 ft) of coal. Estimated bituminous coal reserves in Turkey are 1.3 billion MT; about 5 million MT are produced each year and are used mainly for steel making. The coals have a high volatile and ash content. They are high volatile bituminous coals by the ASTM (American Society for Testing Materials) classification. The coals show semi-bright luster and very fine banding. Clarain, fusain, and durain are common lithotypes; the predominant lithotype is vitrinous clarain. Few thick vitrain bands are present. Some Turkish bituminous coals contain a very high percentage of mineral matter. Clay minerals, pyrite, and calcite are the most common. Ninety polished samples were taken from three different locations--Karadon, Uzulmez, and Kozlu--and analyzed under a reflected light microscope with oil immersion objectives. The Turkish bituminous coals exhibit a complex combination of macerals and microlithotypes. Vitrinite is the most abundant maceral type, and exinite is the least abundant. The presence of a high amount of inertinite macerals and duroclarite as well as virtinertite microlithotypes suggests a lacustrine depositional environment for the coals. Successive coal seams, or even a single coal seam, indicate transgressions and regressions. Turkish bituminous coals match the properties of the Pictou coalfield coals in Canada and the Gondwana coals of South Africa, India, and Australia. End_of_Article - Last_Page 1929------------

Differential thermal and thermogravimetric studies and some trace-element contents of some coals and carbonaceous shales from west-central Sinai, Egypt

DTA, modified DTA, thermogravimetric and spectrochemical analyses were performed on twelve samples of Carboniferous carbonaceous shales and coals and two samples of vitrain (separated from the carbonaceous shale or coal) in west-central Sinai. The analyses indicate that these coals and carbonaceous shales belong to the high-volatile sub-bituminous A coal-rank. Trace-element contents for Pb, Zn, Ga, B, Mn, Ge, Ni, V, Cr, Cu and U are given and averaged. These are then compared with the averages for the only published trace-element contents of the nearby Jurassic Ayun Musa coals. They are found to be richer in Pb, Zn and Ga. Ge is remarkably concentrated in the vitrain bands and seamlets inside the Carboniferous Sinai host-coals while V, Zn and Pb and, to a lesser extent, Mn, Cr and U are depleted in vitrains relative to their host-rocks.

Some aspects of the physical constitution of certain lower Gondwana coal seams of India

The vast majority of Lower Gondwana Barakar coal seams investigated reveal microfragmental character of organic matter rich in durain and duroclarain lithotypes with few thin vitrain bands. They are characterized by fine state of maceral division with significant proportion of sedimentary mineral matter. Inertinite (fusinite, semifusinite and micrinite) is predominant in the coal seams forming 50 to 60 percent of the maceral composition. The distribution pattern of the physical constituents of the coal shows characteristic petrographic assemblages or types indicating many features, which deserve attention during rehabilitation of the material. Predominant fusinization of fossil material and finely dispersed clay minerals suggest decay and decomposition of swamps in addition to peatification. The differing degrees of exposure of organic material may be due to lower ground water level than swamps, indicating drier conditions during the initial phase of coal formation. Subsequent coalification and regional variation in coal types may be explained on the basis of stratigraphic depth and certain igneous rocks commonly seen in the coal seams.