The aromatization (not ring-condensation) is dominant in the period of coalification of low-to-medium rank, and this phenomenon is more remarkable in vitrinite than that in inertinite.

• 在中低变质阶段，对煤化进程起主导作用的的是芳构化作用而不是环缩合作用，但在惰质组中脂碳断裂形成芳环的现象不明显。