| 21. | Coal balls commonly contain dolomites, aragonite, and masses of organic matter at various stages of decomposition.
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| 22. | The acid dissolves the mineral matter from the coal ball, leaving a projecting layer of plant cells.
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| 23. | Coal balls are calcium-rich permineralised life forms, mostly containing magnesium carbonates, pyrite, and quartz.
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| 24. | They stressed the importance of interaction with seawater, believing that it was necessary for the formation of coal balls.
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| 25. | Her process essentially entails heating and then making multiple applications of solutions of paraffin in xylene to the coal ball.
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| 26. | Each subsequent application has a greater concentration of paraffin in xylene to allow the wax to completely pervade the coal ball.
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| 27. | Coal balls in North America were found in Iowa coal seams since the 1890s, ) drew the parallel in 1922.
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| 28. | Stopes made major contributions to knowledge of the earliest angiosperms, the formation of coal balls and the nature of coal macerals.
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| 29. | Other minerals, including gypsum, illite, kaolinite, and lepidocrocite also appear in coal balls, albeit in lesser quantities.
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| 30. | The process required cutting a coal ball with a diamond saw, then flattening and polishing the thin section with an abrasive.
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