Three-Dimensional X-ray Reflections from Anthracite and Meta-Anthracite

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Science  04 Nov 1960:
Vol. 132, Issue 3436, pp. 1314-1316
DOI: 10.1126/science.132.3436.1314


Careful analysis of x-ray scattering intensities of demineralized metaanthracites and high-rank anthracites formed during the Pennsylvanian geological period has revealed the presence of three-dimensional (hkl) reflections of graphite, demonstrating unequivocally that coals graphitize with metamorphism. Graphitization has been observed also with a coal formed before the Cambrian period, much earlier than most coals. A significant degree of graphitization occurs by coalification when the graphite-like layers attain a size of 25 to 30 angstroms as compared to 100 A or more by the heat treatment of amorphous carbons.