Evolution and its stages of the optical properties of high-rank coal macerals in China

QIN YONG, College of Mineral Resources and Environmental Sciences, China University of Mining and Technology Xuzhou 221008 Jiangsu China

Based on more than 400 samples collected form the 22 high-rank mining districts in China and using methods such as microscopic photometry, XRD, EPR and mercury porisimetry, the author made an investigation into the high-rank vitrinite, exinite and inertinite reflectances, giving new insight into the coalification of high-rank coals.
Three stages of the development of maceral reflectances were defined in accordance with the reversals and alternations of the reflectances during coalification as follows:
1st stage or meta-exinitic stage from 2.1-4.5% vitrinite Rmax
2nd stage or meta-vitrinitic stage from 4.5-8.5% vitrinite Rmax
3rd stage or meta-inertinitic stage from 8.5-10.5% vitrinite Rmax.
The end of the 3rd stage marks the end of coalification and the beginning of graphitization.

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