the x-ray diffraction patterns of unmetamorphosed, regionally metamorphosed, thermally metamorphosed and hydrothermally metamorphosed coals have been systematically analysed.
系统分析了广西未变质煤、区域变质煤、巖浆变质煤和热液变质煤的x射线衍射特征。
filtration and diffusion are the major mechanism by which normal coal is changed into hydrothermally metamorphosed coal.