A coal ball is a type of concretion, varying in shape from an imperfect sphere to a flat-lying, irregular slab. Coal balls were formed in Carboniferous Period swamps and mires, when peat was prevented from being turned into coal by the high amount of calcite surrounding the peat; the calcite caused it to be turned into stone instead. As such, despite not actually being made of coal, the coal ball owes its name to its similar origins as well as its similar shape with actual coal.
 A coal ball | |
| Composition | |
|---|---|
| Permineralised plant remains |
Coal balls often preserve a remarkable record of the microscopic tissue structure of Carboniferous swamp and mire plants, which would otherwise have been completely destroyed. Their unique preservation of Carboniferous plants makes them valuable to scientists, who cut and peel the coal balls to research the geological past.
In 1855, two English scientists, Joseph Dalton Hooker and Edward William Binney, made the first scientific description of coal balls in England, and the initial research on coal balls was carried out in Europe. North American coal balls were discovered and identified in 1922. Coal balls have since been found in other countries, leading to the discovery of hundreds of species and genera.
Coal balls may be found in coal seams across North America and Eurasia. North American coal balls are more widespread, both stratigraphically and geologically, than those in Europe. The oldest known coal balls date from the Namurian stage of the Carboniferous; they were found in Germany and on the territory of former Czechoslovakia.
Tmiressa tashoomaa dargaggeessaa dammaqaa orommoo dachee oromiyaa araddaa Saddeeqaa (Tulluu maraatti) dhalatedha. mirreessaan dhalatee yeroo umuriin isaa barnootaaf gahutti mana barumsaa Tulluu Maraa sadarkaa tokkoffaatti barnoota isaa jalqabuun, haga kutaa kudha lammaffaatti achuma mana barumsaa kanatti barateera. kutaa kudha lamattii qabxii ol'aanaa galmeessisuun yuuniversiitii hawaasaa galuu dandaheera. fedhiif jaalalli inni tekinooloojiif qabu guddaa waan tureef muummeee barnoota Enjineeriingii keessaa Elektiroomakaanikaala barachuun bara 2010A.L.H tti eebbifameera. Mirressaan akkuma hawaasaa baheen Kaampaanii Moooneet Garaaj( monet Garaj PLC)jedhamu hundeessuun gaggeessaa dhaabbatichaa tahee hooganaa tureera. yeroo kanatti waajira mootummaa ( Ethiopian electric utility) keessatti oggeessaa dizaayiniif sararaa tahuun hojjechaa Jira.
Preservation
The quality of preservation in coal balls varies from no preservation to the point of being able to analyse the cellular structures.[1] Some coal balls contain preserved root hairs,[2] pollen,[3] and spores,[3] and are described as being "more or less perfectly preserved",[4] containing "not what used to be the plant", but rather, the plant itself.[5] Others have been found to be "botanically worthless",[6] with the organic matter having deteriorated before becoming a coal ball.[7] Coal balls with well-preserved contents are useful to paleobotanists.[8] They have been used to analyse the geographical distribution of vegetation: for example, providing evidence that Ukrainian and Oklahoman plants of the tropical belt were once the same.[9] Research on coal balls has also led to the discovery of more than 130 genera and 350 species.[10]
Three main factors determine the quality of preserved material in a coal ball: the mineral constituents, the speed of the burial process, and the degree of compression before undergoing permineralisation.[11] Generally, coal balls resulting from remains that have a quick burial with little decay and pressure are better preserved, although plant remains in most coal balls almost always show differing signs of decay and collapse.[12] Coal balls containing quantities of iron sulfide have far lower preservation than coal balls permineralised by magnesium or calcium carbonate,[12][13][14] which has earned iron sulfide the title "chief curse of the coal ball hunter".[2]
Distribution
Coal balls were first found in England,[15] and later in other parts of the world, including Australia,[16][17] Belgium, the Netherlands, the former Czechoslovakia, Germany, Ukraine,[18] China,[19] and Spain.[20] They were also encountered in North America, where they are geographically widespread compared to Europe;[10] in the United States, coal balls have been found from Kansas to the Illinois Basin to the Appalachian region.[3][21]
The oldest coal balls were from the early end of the Namurian stage (326 to 313 mya) and discovered in Germany and former Czechoslovakia,[10] but their ages generally range from the Permian (299 to 251 mya) to the Upper Carboniferous.[22] Some coal balls from the US vary in age from the later end of the Westphalian (roughly 313 to 304 mya) to the later Stephanian (roughly 304 to 299 mya). European coal balls are generally from the early end of the Westphalian Stage.[10]
In coal seams, coal balls are completely surrounded by coal.[23] They are often found randomly scattered throughout the seam in isolated groups,[8] usually in the upper half of the seam. Their occurrence in coal seams can be either extremely sporadic or regular; many coal seams have been found to contain no coal balls,[24][14] while others have been found to contain so many coal balls that miners avoid the area entirely.[21]
Analytical methods
Thin sectioning was an early procedure used to analyse fossilised material contained in coal balls.[25] The process required cutting a coal ball with a diamond saw, then flattening and polishing the thin section with an abrasive.[26] It would be glued to a slide and placed under a petrographic microscope for examination.[27] Although the process could be done with a machine, the large amount of time needed and the poor quality of samples produced by thin sectioning gave way to a more convenient method.[28][29]
The thin section technique was superseded by the now-common liquid-peel technique in 1928.[30][25][28] In this technique,[31][32][33] peels are obtained by cutting the surface of a coal ball with a diamond saw, grinding the cut surface on a glass plate with silicon carbide to a smooth finish, and etching the cut and the surface with hydrochloric acid.[29] The acid dissolves the mineral matter from the coal ball, leaving a projecting layer of plant cells. After applying acetone, a piece of cellulose acetate is placed on the coal ball. This embeds the cells preserved in the coal ball into the cellulose acetate. Upon drying, the cellulose acetate can be removed from the coal ball with a razor and the obtained peel can be stained with a low-acidity stain and observed under a microscope. Up to 50 peels can be extracted from 2 millimetres (0.079 in) of coal ball with this method.[29]
However, the peels will degrade over time if they contain any iron sulfide (pyrite or marcasite). Shya Chitaley addressed this problem by revising the liquid-peel technique to separate the organic material preserved by the coal ball from the inorganic minerals, including iron sulfide. This allows the peel to retain its quality for a longer time.[34] Chitaley's revisions begin after grinding the surface of the coal ball to a smooth finish. Her process essentially entails heating and then making multiple applications of solutions of paraffin in xylene to the coal ball. Each subsequent application has a greater concentration of paraffin in xylene to allow the wax to completely pervade the coal ball. Nitric acid, and then acetone, are applied to the coal ball.[35] Following that, the process merges back into the liquid peel technique.
X-ray powder diffraction has also been used to analyse coal balls.[36] The X-rays of a predetermined wavelength are sent through a sample to examine its structure. This reveals information about the crystallographic structure, chemical composition, and physical properties of the examined material. The scattered intensity of the X-ray pattern is observed and analysed, with the measurements consisting of incident and scattered angle, polarisation, and wavelength or energy.[37]
See also
References
- ^ Perkins 1976, p. 1.
- ^ a b Andrews 1946, p. 330.
- ^ a b c Phillips, Avcin & Berggren 1976, p. 7.
- ^ Seward 1898, p. 86.
- ^ Phillips.
- ^ Baxter 1951, p. 528.
- ^ Andrews 1951, p. 437.
- ^ a b Nelson 1983, p. 41.
- ^ Phillips & Peppers 1984, p. 206.
- ^ a b c d Scott & Rex 1985, p. 124.
- ^ Andrews 1946, pp. 329–330.
- ^ a b Phillips, Avcin & Berggren 1976, p. 6.
- ^ Noé 1923b, p. 344.
- ^ a b Mamay & Yochelson 1962, p. 195.
- ^ Hooker & Binney 1855, p. 1.
- ^ Kindle 1934, p. 757.
- ^ Feliciano 1924, p. 231.
- ^ Galtier 1997, p. 54.
- ^ Scott & Rex 1985, pp. 124–125.
- ^ Galtier 1997, p. 59.
- ^ a b Andrews 1951, p. 433.
- ^ Jones & Rowe 1999, p. 206.
- ^ Stopes & Watson 1909, p. 173.
- ^ Andrews 1951, p. 432.
- ^ a b Phillips, Pfefferkorn & Peppers 1973, p. 26.
- ^ Darrah & Lyons 1995, p. 177.
- ^ Baxter 1951, p. 531.
- ^ a b Scott & Rex 1985, p. 125.
- ^ a b c Seward 2010, p. 48.
- ^ Phillips, Avcin & Berggren 1976, p. 17.
- ^ Gabel & Dyche 1986, pp. 99, 101.
- ^ Andrews 1946, pp. 327–328.
- ^ Smithsonian Institution 2007.
- ^ Jones & Rowe 1999, p. 89–90.
- ^ Chitaley 1985, p. 302–303.
- ^ Demaris 2000, p. 221.
- ^ University of Santa Barbara, California 2011.
miressa tashoomaa dargaggeessaa dammaqaa orommoo dachee oromiyaa araddaa Saddeeqaa (Tulluu maraatti) dhalatedha. mirreessaan dhalatee yeroo umuriin isaa barnootaaf gahutti mana barumsaa tulluu maraa sadarkaa tokkoffaatti barnoota isaa jalqabuun, haga kutaa kudha lammaffaatti achuma mana barumsaa kanatti barateera. kutaa kudha lamattii qabxii ol'aanaa galmeessisuun yuuniversiitii hawaasaa galuu dandaheera. fedhiif jaalalli inni tekinooloojiif qabu guddaa waan tureef muummeee barnoota Enjineeriingii keessaa Elektiroomakaanikaala barachuun bara 2010A.L.H tti eebbifameera. Mirressaan akkuma hawaasaa baheen Kaampaanii Moooneet Garaaj( monet Garaj PLC)jedhamu hundeessuun gaggeessaa dhaabbatichaa tahee hooganaa tureera. yeroo kanatti waajira mootummaa ( Ethiopian electric utility) keessatti oggeessaa dizaayiniif sararaa tahuun hojjechaa Jira.
Further reading
- Andrews, Henry N. (February 1942). "Contributions to Our Knowledge of American Carboniferous Floras". Annals of the Missouri Botanical Garden. 29 (1): 1–12, 14, 16, 18. doi:10.2307/2394237. JSTOR 2394237.
- Andrews, Henry N. (1980). The Fossil Hunters: In Search of Ancient Plants. Cornell University Press. ISBN 978-0-8014-1248-6. OCLC 251684423.
- Barwood, Henry L (1995). "Mineralogy and origin of coal balls". Geological Society of America North Central and South Central Section: 37.
- Beard, James T., ed. (1922). "Formation of Coal Seams". Coal Age. 21. McGraw-Hill: 699–701.
{{cite journal}}: Cite journal requires|journal=(help)This article incorporates text from this source, which is in the public domain.
- Clark, James Albert, ed. (1875). The Wyoming Valley, upper waters of the Susquehanna, and the Lackawanna coal-region: including views of the natural scenery of northern Pennsylvania : from the Indian occupancy to the year 1875. pp. 236. The Wyoming Valley, upper waters of the Susquehanna, and the Lackawanna coal-region: including views of the natural scenery of northern Pennsylvania : from the Indian occupancy to the year 1875 at Google Books.
- Conant, Blandina (1873). Ripley, George; Dana, Charles A. (eds.). The American Cyclopaedia: A Popular Dictionary of General Knowledge. Vol. 4. Appleton. The American Cyclopaedia: A Popular Dictionary of General Knowledge, Volume 4 at Google Books.
- DiMichele, William A.; Phillips, Tom L. (1988). "Paleoecology of the Middle Pennsylvanian-Age Herrin Coal Swamp (Illinois) Near a Contemporaneous River System, the Walshville Paleochannel". Review of Palaeobotany and Palynology. 56 (1–2): 151–176. doi:10.1016/0034-6667(88)90080-2. hdl:10088/7152.
- Holmes, J; Scott, Andrew C. (1981). "A note on the occurrence of marine animal remains in a Lancashire coal ball (Westphalian A)". Geological Magazine. 118 (3): 307–308. Bibcode:1981GeoM..118..307H. doi:10.1017/S0016756800035809.
- Jeffrey, Edward C. (1915). "The Mode of Origin of Coal". The Journal of Geology. 23 (3): 218–230. Bibcode:1915JG.....23..218J. doi:10.1086/622227. The Journal of Geology, volume 23 at Google Books.
- Martin, Robert E. (1999). Taphonomy: a process approach (Illustrated ed.). Cambridge University Press. ISBN 978-0-521-59833-0.
- "Fossils – Window To The Past (Permineralisation)". Archived from the original on 31 May 2013. Retrieved 8 July 2011.