Enrichment of arsenic, antimony, mercury, and thallium in a Late Permian anthracite from Xingren, Guizhou, Southwest China

Mineralogy and geochemistry of nine Late Permian coal-seam channel samples (anthracite) from Xingren, Guizhou, Southwest China were examined. Results showed that As, Sb, Hg, and Tl are significantly enriched in a Late Permian anthracite (sample XR-M1) in the study area, and their contents are as high as 2226 μg/g, 3860 μg/g, 12.1 μg/g, and 7.5 μg/g, respectively. However, the contents of the four elements in other coal-seam channel samples from Xingren, even the two channel samples (samples XR-M2 and XR-M3) that are from the same bed as sample XR-M1, are close to the ordinary coal average, indicating that these four elements varied greatly in different coal beds and different locations of the same bed, and such coals highly enriched in these hazardous elements are very local and restricted. The main carrier of As, Sb, Hg, and Tl in sample XR-M1 is an epigenetic getchellite rather than syngenetic pyrite and clay minerals. Getchellite occurs only in the veined kaolinite of hydrothermal origin. The high As, Sb, Hg, and Tl in coal are derived from an arsenic- and antimony-rich hydrothermal fluid.