Distributions of Minor and Trace Elements in Chinese Coals_百度...答:Most minor and trace elements in Early-Middle Jurassic coals are low er than in other coals,for example,Sb,Zn,Cr,and Th. Most minor and trace elements in Late Per- mian coals such as Cd,As,Sb,Fe,Co,Ni,Mo,Se,Cr and Cu are enriched. The contents of Pb,Cl,Br and Th are higher ...