GEOCHEMICAL CHARACTERISTICS OF THE GONGYI BAUXITE DEPOSIT IN HENAN PROVINCE

Longmen-Gongyi area is one of the bauxite metallogenic belts in Henan Province. Based on chemical test of the main compositions of Gongyi bauxite deposit, the paper analyzes the change rule of elements in the bauxite deposit. The results show that the major mineral compositions of bauxite ore is diaspore(45%-95%), followed by kaolinite and illite(4%-25%), with a small amount of siderite, pyrite, calcite and dolomite, and trace minerals such as zircon and apatite. The main chemical compositions of bauxite ore are Al₂O₃, SiO₂, Fe₂O₃, TiO₂ and S, accounting for 83.42% of the total, among which the Al₂O₃ content is 40.46%-77.59%, averagely 60.68%, SiO₂ 1.00%-29.54%, averagely 14.07%, with the aluminum-silicon ratio (A/S) of 1.8-65.1, averagely 4.3. Under different burial depth conditions, the larger the relative depth is, the larger the Al₂O₃ content and A/S ratio are. The chemical index of alteration (CIA) of the area is up to 91.16, indicating that the aluminum-bearing rock series in the area has undergone intense chemical weathering.