COMPARATIVE PETROGRAPHY OF OMBILIN AND BAYAH COALS RELATED TO THEIR ORIGIN

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1 COMPARATIVE PETROGRAPHY OF OMBILIN AND BAYAH COALS RELATED TO THEIR ORIGIN ABSTRACT Binarko Santoso and Bukin Daulay R&D Cene for Mineral and Coal Technology Jalan Jenderal Sudirman Bandung 0 Ph. 000, fax. 000, binarkos@tekmira.esdm.go.id Two coalfields have been conasted and compared on the basis of qualitative and quantitative studies of macerals and minerals. The peological comparison of the coals indicates that the viinite and liptinite contents of the Ombilin coal are higher than those of the Bayah coal. The inertinite content of both coals is somewhat similar. The mineral matter of the Bayah coal is higher than the Ombilin coal. The viinite reflectance and rank of the Ombilin coal is higher and thus, its coal rank (subbituminous to anthracite) is better than that of the Bayah coal (subbituminous to medium volatile bituminous). A clear distinction between the Ombilin and Bayah coals is not possible with peographic methods alone, and other geological parameters have to be considered. The maceral compositions of the Ombilin and Bayah coals are slightly different from each other due to inusion effect. In the thermally affected coals from both areas, liptinite generally cannot be distinguished from viinite and therefore it appears to contain high proportion of viinite (>0%). However, thermally unaffected coals from both coalfields contain <0% of viinite. Liptinite maceral is common in coals unaffected by contact alteration with some samples containing up to 0%. In conast, thermally affected coals have ace amounts of liptinite. Both thermally affected and affected coals contain rare inertinite with some samples containing up to %. In some cases, coals with high inertinite content have a relatively high amount of mineral matter. The Ombilin and Bayah coals show variable viinite reflectances, due to igneous inusion factor. Coal of lower rank has been metamorphosed to bituminous or anthracitic ranks. The extent of rank increase depends primarily on distance from the inuding igneous rock, but it may also be related to size and temperature of the inusion. As the viinite reflectance (Rvmax) values of the Ombilin coal (0..%) are higher as compared with the Bayah coal (0..%), this suggests that the heat source to the thermally affected coals is closer in the Ombilin coal than that of in the Bayah coal. Keywords: Ombilin, Bayah, comparative peography, coal. INTRODUCTION The maceral compositions of the various Indonesian Tertiary coals are slightly different one to another. Factors that cause these variations include inusion effects and age. In thermally affected coals from the Ombilin and Bayah coalfields for this study, liptinite or exinite generally cannot be distinguished from viinite. As a result, it appears to contain high proportions of viinite, which contains >0%. On the other hand, thermally unaffected coals from those coalfields contain <0% of viinite. The rank of coal is usually considered to be largely conolled by the level of temperature under confining pressure, reached by the organic matter and partly by the time during which the effects were maintained (Teichmuller and Teichmuller, ). Increased depth of burial and increased temperature and pressure over a period of time consequently result in higher rank. Igneous activity can locally increase the supply of heat and cause increases in the rank of nearby coal seams. For these interesting phenomena for characteristics of the coals, the study is aimed at obtaining an understanding of the following aspects as follows: a) to determine type and rank characteristics of the coals by establishing maceral analyses and reflectance measurements, b) to examine the effect of igneous inusion to the type and rank of the coals, and c) to compare the peology of the coals. To achieve the aims, analyses of the Ombilin and Bayah coalfields are included in the present study.. ANALYTICAL METHOD The coal samples for this study were collected from borehole cores and spot samples of the Tertiary Ombilin and Bayah coalfields. The procedures, preparation, terminology and techniques used for the study are based on the Standards Association of Ausalia (,,,, a, b, and ). Thirtysix () coal samples from the Ombilin coalfield and twentyone () coal samples from the Bayah coalfield were prepared for peographic examination according to the techniques developed in the coal laboratory, Research and Development Cene for Mineral and Coal Technology.

2 The method of preparation of polished particulate coal mounts for microscopic analysis includes crushing, embedding, grinding and polishing. The microscopic examination of the polished blocks was undertaken by using a reflected light Leitz Orthoplan microscope fitted with a fluorescence mode. The maceral analysis is based on counting of 00 points using the Swift Automatic Point Counter attached to the microscope. The maceral data are calculated as follows: mineral matter counted: % viinite + liptinite + inertinite + mineral matter = 00 mineral matter free basis: % viinite + liptinite + inertinite = 00 The measurements on viinite reflectance were carried out based on 00 points obtained on each sample from which the mean random reflectance (Rvrnd) and the standard deviation (s) were calculated. In addition, a total of 0 measurements were taken on each sample from which the mean maximum reflectance (Rvmax) and deviation (s) were also calculated.. GEOLOGICAL SETTING.. Ombilin According to De Coster (), Harsa () and Koning () the Ombilin Coalfield situated on the northwest margin of the Eocene Ombilin Basin in cenal west Sumatera is sucturally conolled by wrench faulting related to the Great Sumatera Fault Zone (Figure ). Figure. Ombilin intermontane Basin (Koning, ) The Palaeogene cycle of sedimentation in the basin indicates the initial terresial phase of the Tertiary sequence (Koesoemadinata, ; Eubank and Makki, ). The Palaeogene sequence was deposited in an intermontane basin that developed at the beginning of the Tertiary when the pretertiary landmass was blockfaulted into grabens. The grabenlike basin was filled from all sides by alluvial fans, while several lakes existed in the cenal basin. As the topographic relief decreased, the basin became an alluvial valley with meandering rivers followed by a braided river system prior to be folded and uplifted in the Early Miocene. A number of subparallel anticlines and synclines are present in the basin, mostly bounded by major faults, which end principally eastwest, northeastsouthwest and northwestsoutheast. The coal measures occur in two satigraphic units: the Sawahlunto Formation and the Poro Member of the Sawahtambang Formation. Three coal seams (A, B and C) occur in the Sawahlunto Formation (Figure ). Coal seams of the Poro Member of the Sawahtambang Formation are exposed on the southeast part of the basin. The seams are very thin ( to cm thick)... Bayah According to Koesoemadinata (), Palaeogene and Neogene coals are not well developed in Jawa. Terresial preansgressive sedimentation occurred in Banten only (Bayah, Cihideung and Cimandiri areas, and resulted in coal deposition, whereas in Cenal and East Jawa sedimentation was associated with a marine ansgression that occurred over the pretertiary basement. The Palaeogene coals include in a monotonous series of quartzsandstones (partly conglomeratic) and claystones of the Bayah Formation (Figures and ). The Eocene sediments are songly folded, particularly in the Cimandiri area. In this area, the coal seams

3 Figure. Satigraphic sequence of the Ombilin coal measures (MarubeniKaiser, ) Cimandiri Bayah Cihideung Figure. Tectonic map of Banten and West Jawa showing the studied areas (Darman and Sidi, 000).

4 Figure. Satigraphic diagram of the Banten area (Katili and Koesoemadinata, ). reach dips of up to 0º (Koesoemadinata and Matasak, ). Some small andesite inusions occur in Cimandiri. The coal seams rare exceed a thickness of one mee, and exceptionally are two mees thick. Up to nine seams occur in some sections (Koesoemadinata and Matasak, ). In some localities, the coals are highly lenticular. No reliable indexsata are available for correlation of the various coal measures. The Neogene coal seams occur in an upper Miocene tuffaceous series that consists of sandstones, mudstones, conglomerates, pumiceous and quartzbearing tuffs and tuffbreccias.. PETROLOGY.. Ombilin Peographic studies of coal samples from four coal seams namely: A, B, B and C in the Ombilin Coalfield illusate that all samples are composed mainly of viinite and liptinite with inertinite being rare (Table ). Slightly different maceral compositions exist between coal seams. For example, viinite content increases slightly from seam A through to seam C. Thermally affected coals commonly contain viinite and rare inertinite, but no recognisable liptinite. Viinite content in the Ombilin coals has a range between 0% and %, with average of 0%. Deoviinite forms a maix for isolated thin bands of teloviinite and for liptinite (Figure ). The deoviinite maix comprises >0% of the total viinite in most of the coal samples. Geloviinite (mainly corpoviinite and porigelinite) takes place throughout the coals, which are commonly associated with suberinite. Liptinite content varies from % to %, with average of %. Cutinite, resinite and liptodeinite are the dominant liptinite macerals, although suberinite and sporinite are dominant in some occurrences. Fluorinite, exsudatinite and alginite occur in a few samples and are rare. Cutinite constitutes over % of some samples and occurs mostly as thinwalled cutinite (tenuicutinite). The cutinite has weak to moderate intensity orange fluorescence (Figures and ), and in some cases, it does not fluoresce. Liptodeinite constitutes up to % of some samples in the Ombilin coals. The liptodeinite has low reflectance and yellow to orange fluorescence. Resinite is present in most of the samples, although its content is ace to %. The resinite occurs as discrete small bodies (<0.0 mm). It has greenish yellow to yellow fluorescence. Suberinite constitutes >% of some coal samples. It typically shows weak orange fluorescence, but in some cases it does not fluoresce. Nonfluorescing suberinite is difficult to distinguish from viinite. Sporinite is a dominant liptinite maceral in some samples. It has yellow to orange fluorescence. Fluorinite is rare in the coals. It has greenish yellow fluorescence. Alginite is present in some samples. Its content is variable, ranging from ace to %. It has yellow to orange fluorescence. Significant variation in liptinite fluorescence colours exists between the samples.

5 Table. Maceral composition of the Ombilin coals LOCATION SEAM VITRINITE (%) INERTINITE (%) LIPTINITE (%) Tanah Hitam o/c Sawah Rasau u/g Tanah Hitam o/c Sawah Rasau u/g Tanah Hitam o/c Sawah Rasau u/g BH Parambahan Tanah Hitam o/c Sawah Rasau u/g BH Parambahan Notes: Tv Dv Gv Tot Sf Scl Inert Tot Res Cut Sub Tot A 0 0 A B B B B B 0 C 0 C C Tv : teloviinite, Dv : deoviinite, Gv : geloviinite, Sf : semifusinite, Scl : sclerotinite, Inert : inertodeinite, Res: : resinite, Cut : cutinite, Sub : suberinite, MM : mineral matter, Tot : total o/c : open cut, u/g : underground MM (%) Figure. Deoviinite (grey), liptinite (black) and pyrite (white) of the Ombilin coal. Rvmax: 0.%, field width: 0. mm, reflected white light

6 Figure. Cutinite (black) in viinite (grey) of the Ombilin coal. Rvmax: 0.%, field width: 0. mm, reflected white light Figure. Cutinite (yellow) in viinite (black) of the Ombilin coal. Rvmax: 0.%, field width: 0. mm, fluorescence mode Inertinite is a minor constituent in the samples. The inertinite content varies between a ace and %, with average of %. Sclerotinite is the dominant inertinite group maceral consisting of sclerotia, single and twincelled teleutospores and teleutospores with three and four cells. Semifusinite occurs as thin layers and rarely as isolated lenses in deoviinite maix. Inertodeinite constitutes % (average) of the Ombilin coals. It occurs as angular and irregular forms disseminated throughout the coals. Mineral matter includes mainly clay and pyrite and is rare in the Ombilin coals. It generally constitutes a ace to %. Most of the mineral matter occurs as pods disseminated throughout the coals. Framboidal pyrite (see Figure ) is common in the thinner seam. The liptinite and inertinite contents of the Ombilin coals are systematically related to viinite content. The liptinite and inertinite contents decrease with increase in viinite content. The liptinite content is not related to the inertinite content. Mean maximum viinite reflectance (Rvmax) values were obtained on thirtysix samples from Sawahlunto Formation of Ombilin Coalfield (Table ). Most of the samples are high volatile bituminous rank (Rvmax of 0.0.%), although one sample is subbituminous (Rvmax of 0.%). The low viinite reflectance value of some samples may be due to the presence of alginite (Hutton and Cook, 0). The rank of the isolated coals increases sharply into anthracite stage. This change is presumably associated with heating from a local inusion... Bayah Maceral analyses of twentyone Bayah coals show that viinite is the dominant maceral over liptinite, and inertinite is rare. Mineral matter (mainly clay and pyrite) is significantly high (Table ). Viinite of the coals varies between % and % (average of %). The viinite mostly occurs as thick layers with deoviinite maix interbedded with thin layers of teloviinite (Figure ). Geloviinite including corpoviinite and porigelinite is present throughout the coals. Cutinite and resinite are the dominant maceral liptinite macerals. Sporinite, suberinite, liptodeinite, fluorinite and exsudatinite are present in some samples. Cutinite is the dominant liptinite maceral (up to %)

7 Table. Rank of the Ombilin coals (Ausalian standard) LOCATION SEAM Rvmax (%) RANGE RANK Tanah Hitam o/c A Sawah Rasau u/g A Tanah Hitam o/c B Sawah Rasau u/g B Tanah Hitam o/c B Sawah Rasau u/g B BH Parambahan B Tanah Hitam o/c C Sawah Rasau u/g C BH Parambahan C Subbituminous Anthracite Anthracite Notes: o/copen cut, u/g: underground LOCATION Notes: Bayah Cimandiri Cihideung Table. Maceral composition of the Bayah coals VITRINITE (%) INERTINITE (%) LIPTINITE (%) MM (%) Tv Dv Gv Tot Sf Scl Inert Tot Res Cut Sub Tot Tv : teloviinite, Dv : deoviinite, Gv : geloviinite, Sf : semifusinite, Scl : sclerotinite, Inert : inertodeinite, Res : resinite, Cut : cutinite, Sub : suberinite, MM : mineral matter, Tot : total 0 0 0

8 Figure. Teloviinite (grey, long) interbedded with deoviinite (grey, short) and clays (black) of the Bayah coal. Rvmax: 0.0%, field width: 0. mm, reflected white light and mostly occurs as thin cuticles (Figure ). It has greenish yellow to yellow fluorescence. Resinite, the other dominant liptinite maceral (up to %) occurs as discrete small bodies (<0.0 mm) of various shapes. The resinite has the same fluorescence as the cutinite. Sporinite constitutes a ace to % and it has greenish yellow to yellow fluorescence. Suberinite is rare in the coals and has weak yellow to orange fluorescence, but in some cases it does not fluoresce. Liptodeinite and fluorinite are rare in the coals having the same fluorescence as greenish yellow. Both are disseminated throughout the coals. Exsudatinite is also rare in the coals occurring mostly infilling joints or beddingplane cracks. The exsudatinite has song greenish yellow to yellow fluorescence (Figures 0 and ). Figure. Cutinite (black) and viinite (grey) of the Bayah coal. Rvmax: 0.%, field width: 0. mm, reflected white light Figure 0. Exsudatinite (black) infilling the fractures of viinite (grey). Rvmax: 0.%, field width: 0. mm, reflected white light

9 Figure. Exsudatinite (yellow) infilling the fractures of viinite (black). Rvmax: 0.%, field width: 0. mm, fluorescence mode Inertinite maceral of the coals includes semifusinite, sclerotinite and Inertodeinite. The semifusinite content is up to %; the sclerotinite and inertodeinite are up to %. Both sclerotinite and inertodeinite are scattered throughout the coals. The sclerotinite includes single and twincelled teleutospores and sclerotia. Some cell lumens are in filled by mineral matter. The inertodeinite occurs as small high reflecting particles (<0.0 mm). Mineral matter of the coals are mainly clay and pyrite varying between % and % (average of %) with few samples containing up to % mineral matter. The clay and pyrite (consisting of framboidal and massive grain suctures) mostly occur as pods disseminated throughout the coals. In some cases, they infill cell lumens. The viinite, liptinite and inertinite contents of the Bayah coals are systematically related to each other. The liptinite and inertinite contents decrease with increases in viinite content. The liptinite content tends to increase in inertinite content. Twentyone coal samples were examined for viinite reflectance and the result is given in Table. The coals range from subbituminous to high volatile bituminous rank (Rvmax between 0.% and 0.%). In some areas, viinite reflectance of the coals increases locally (ranging from 0.% to.%). This change is associated with an igneous inusion.. COMPARATIVE PETROGRAPHY The peology in terms of type and rank of the Ombilin and Bayah coals is compared with one another. Table shows maceral composition and rank of the coals. The viinite content of the Ombilin coal is higher (0.%) than the Bayah coal. The viinite group of these coals is dominated by deoviinite, teloviinite and geloviinite. However, the deoviinite is somewhat higher in the Ombilin coal. The liptinite content is relatively low in all the coals, which are respectively.% in the Ombilin and.% in the Bayah coals. Both of these coals are dominated by cutinite, resinite and suberinite. Like the liptinite content, the inertinite content of all the coals is also relatively low that are % in the Ombilin and.% in the Bayah coals. Sclerotinite, inertodeinite and semifusinite are the most common macerals of the inertinite group present in the coals. However, the sclerotinite is more dominant in the Ombilin coal and the semifusinite is more dominant in the Bayah coal. The mineral matter consists of clay and pyrite that is present in the coals and the higher content is in the Bayah coal (.%) compared with the Ombilin coal (.%). The viinite reflectance (Rvmax) values of the Ombilin coal (0..%) are higher as compared with the Bayah coal (0..%). The Ombilin coal is subbituminous to anthracite according to the Ausalian classification and subbituminous C to anthracite of the ASTM classification. The Bayah coal is subbituminous to medium volatile bituminous based on the Ausalian classification and subbituminous C to medium volatile bituminous of the ASTM values. The maceral compositions of the Ombilin and Bayah coals are slightly different from each other. Two factors can account for these variations, which are inusion effect and age. In the thermally affected coals from both areas, liptinite generally cannot be distinguished from viinite and therefore it appears to contain high proportion of viinite (>0%). However, thermally unaffected coals from both coalfields contain <0% of viinite. Liptinite maceral is common in coals unaffected by contact alteration with some samples containing up to 0%. In conast, thermally affected coals have ace amounts of liptinite. Both thermally affected and

10 Table. Rank of the Bayah coals (Ausalian standard) LOCATION Rvmax (%) RANGE RANK Bayah Cimandiri Cihideung Subbituminous Subbituminous Subbituminous Subbituminous Medium volatile bituminous Table. Maceral composition, mineral matter content, viinite reflectance and rank of the Ombilin and Bayah coals Viinite Liptinite Inertinite Mineral Matter MACERAL GROUP OMBILIN BAYAH Mean content (%) Range (%) Common macerals Mean content (%) Range (%) Common macerals Mean content (%) Range (%) Common macerals Mean content (%) Range (%) Common minerals 0. 0 Dv, Tv, Gv. Cut, Res, Sub Scl, Inert, Sf. Cl, Py. Tv, Dv, Gv. 0 Cut, Res, Sub. Sf, Scl, Inert. Cl, Py Viinite Reflectance Rvmax (%) Rank Ausalian Classification ASTM Subbit.Anthracite Subbit.CAnthracite Subbit.Med. vol. bit. Subbit. CMed.vol.bit. Notes: Tv : teloviinite, Dv : deoviinite, Gv : geloviinite, Sf : semifusinite, Scl : sclerotinite, Inert : inertodeinite, Res : resinite, Cut : cutinite, Sub : suberinite, MM : mineral matter, : ace, bit. : bituminous, vol. : volatile, Med. : medium affected coals contain rare inertinite with some samples containing up to %. In some cases, coals with high inertinite content have a relatively high amount of mineral matter. Cook and Johnson () have suggested that this may be the result of peat ablation in relatively oxidising environments giving an unfavourable balance between the rate of accumulation of organic material and mineral matter. The dominance of viinite in the Ombilin and Bayah coals is indicative of forest type vegetation in humid opical zone, without significant dry events throughout. Viiniterich coal in some cases has a high content of mineral matter. A number of authors including Cook (), Shibaoka and Smyth () have noted that many seams deposited in areas of rapid subsidence have both a high viinite content and a high mineral content present as discrete dirt bands. In addition, the maceral and mineral composition of the Ombilin and Bayah coals is somewhat similar to one another, in which the viinite content is absolutely dominant in the coals. This suggests that these coals were formed in anaerobic and wet environment. However, the Ombilin coal was deposited in somewhat wetter condition which prevailed during the deposition of the coal. Despite their short geological history, the Ombilin and Bayah coals exhibit variable viinite reflectances, apparently due to variable tectonic and igneous inusion factors. In these areas, a more rapid and thorough alteration has taken place where bodies of igneous rock have inuded the Tertiary sequence. As a result, coal of lower rank has been metamorphosed to bituminous or anthracitic ranks. The extent of rank increase depends primarily on distance from the inuding igneous rock, but it may also be related to size and 0

11 temperature of the inusion. The extent of gas or liquid seaming away from inusion may also be significant. As the viinite reflectance (Rvmax) values of the Ombilin coal (0..%) are higher as compared with the Bayah coal (0..%), this suggests that the heat source to the thermally affected coals is closer in the Ombilin coal than that of in the Bayah coal.. CLOSING REMARKS The coal type of Ombilin coal illusates some similarities with that of Bayah coal. The main difference between the two coalfields is the proportion of mineral matter content. Both the coals have high content of viinite with the Ombilin coal is somewhat higher. The coals are low in liptinite and inertinite contents. This suggests that these coals were formed in anaerobic and wet environment, where the Ombilin coal was deposited in somewhat wetter condition which prevailed during the deposition of the coal. The coals with high inertinite content have a relatively high amount of mineral matter. It suggests that this may be the result of peat ablation in relatively oxidising environment giving an unfavourable balance between the rate of accumulation of organic material and mineral matter (Cook and Johnson, ). The Ombilin and Bayah coals have viinite reflectances in the range of 0..% and 0..% respectively. The coals consist of thermally unaffected and affected ones. However, viinite reflectances for most of the coals (subjected to regional coalification only) are in the range of 0.0.%. The coals are dominated by subbituminous and high volatile bituminous. However, some are anthracite. Localised contact metamorphism from igneous inusions has caused some of the coals to reach rank in the bituminous to anthracite range. The ranks of the coals are generally considered to be largely conolled by the level temperature under confining pressure. Igneous activity can locally increase the supply of heat and cause increases in the rank of nearby coal seams (Jones et al, ). REFERENCES Cook, A.C.,. The spatial and temporal variation of the type and rank of Ausalian coals. In: Cook, A.C. (ed.), Ausalian black coalits occurrence, mining, preparation and use. Ausalasian Institute of Mineral and Metallurgy, Illawara Branch. Cook, A.C. and Johnson, R.D.,. Seam thickness, quality and sucture variations in the Bulli coal, Sydney Basin, NSW. Ausalasian Institute of Metallurgical Conference. South Ausalia. De Coster, G.L.,. The geology of the Cenal and South Sumatera Basins. Proceedings of Indonesian Peoleum Association, rd Annual Convention. Jakarta. Darman, H. and Sidi, F.H., 000. An outline of the geology of Indonesia. Indonesian Association of Geologists. Jakarta. Eubank, R.T. and Makki, C.A.,. Suctural geology of the Cenal Sumatera backarc basin. Indonesian Peoleum Association, 0 th Annual Convention. Jakarta. Harsa, E.,. Some of the factors which influence oil occurrence in the South and Cenal Sumatera Basins. Regional Conference on the geology and mineral resources of Southeast Asia. Jakarta (unpublished). Hutton, A.C. and Cook, A.C., 0. Influence of alginite on the reflectance of viinite from Joadja NSW and some other coals and oil shales containing alginite. Fuel,. Jones, J.M., Davis, A., Cook, A.C. and Murchison, D.G.,. Provincialism and correlation between some properties of viinite. International Journal of Coal Geology,. Katili, J.A. and Koesoemadinata, R.P.,. Suctural pattern of South Banten and its relation to the orebearing veins. Department of Geology, University of Indonesia, Bandung. Koesoemadinata, R.P.,. Sedimentary framework of Tertiary coal basins of Indonesia. rd Regional Conference on geology and mineral resources of Southeast Asia. Bangkok. Koesoemadinata, R.P. and Matasak, T.,. Penelitian endapan batubara di sekitar BayahJawa Barat. Institut Teknologi Bandung. Bandung. Koning, T.,. Peoleum geology of the Ombilin intermontane basin, West Sumatera, IPA th Annual Meeting Conference. Marubeni Iida and Kaiser Steel,. Ombilin coalfield, West Sumatera, Indonesia. Technical report of investigation and exploration, Marubeni Iida Co.Ltd. and Kaiser Steel International Mining Corp. (unpublished). Shibaoka, M. and Smyth, M.,. Coal peology and the formation of coal seams in some Ausalian sedimentary basins. Economic Geology, 0. Standards Association of Ausalia,. Ausalian standard code of recommended practice for taking samples from coal seams in situ. AS CK. Standards Association of Ausalia,. Glossary of terms for coal and coke. ASK. Standards Association of Ausalia,. Methods for the analysis and testing of coal and coke: reporting of results. AS 0 (). Standards Association of Ausalia,. Code of practice for preparation of hard coal samples for microscopical examination by reflected light. AS 0.

12 Standards Association of Ausalia, a. Determination of the maceral group composition of bituminous coal and anthracite (hard coal) AS. Standards Association of Ausalia, b. Microscopical determination of the reflectance of coal macerals. AS. Standards Association of Ausalia,. Guide for the taking of samples from hard coal seams in situ. AS. Standards Association of Ausalia,. Coal maceral analysis. AS. Teichmuller, M. and Teichmuller, R.,. The geological basis of coal formation. In: Stach, E. et al. (editors), Stach s textbook of coal peology. Stuttgart.