Mineralogical and compositional characteristics of Late Permian coals from an area of high lung cancer rate in Xuan Wei, Yunnan, China: Occurrence and origin of quartz and chamosite - Dai, S.; Tian, L.; Chou, C.; Zhou, Y.; Zhang, M.; Zhao, L.; Wang, Jingyuan; Yang, Z.; Cao, H.; Ren, D. (International Journal of Coal Geology, 2008)