title: Three-Dimensional X-ray Reflections from Anthracite and Meta-Anthracite.
abstract: 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.
authors.forename: S
authors.initials: S
authors.lastname: Ergun
authors.forename: M
authors.initials: M
authors.lastname: Mentser
authors.forename: H J
authors.initials: HJ
authors.lastname: O'donnell