MINERALOGY AND GEOCHEMISTRY OF THE BAUXITE DEPOSITS (CRETACEOUS), WILKINSON COUNTY, GEORGIA

The Cretaceous bauxite deposits in Hall and Veneer mines, Wilkinson County, Georgia are composed of kaolinite, goethite, gibbsite, anatase, nordstrandite and boehmite. Micas and quartz are absent in the samples. The mineralogy, major element determinations and trace element analysis (Zr in particular) of the Cretaceous bauxite deposits in the Hall and Veneer Mines are consistent with an intense post depositional weathering in the recharge oxic zone where these bauxite deposits are found. Intense weathering origin of the bauxite deposits in the mines are also supported by the extremely high values of the Chemical Index of Alteration (CIA) which is over 99, and the low values of the alkali metals and alkali earth metals. In the Hall and Veneer mines, there is evidence of deposition of bauxite sediments based on non uniform TiO₂/Al₂O₃ values which represent the accumulation of transported materials from contrasting source areas and the presence of pisoids. Kaolin minerals in the Hall and Veneer mines were first produced by the hydrolytic weathering of aluminous sediments and then gibbsite was formed as these early kaolin minerals were desilicated to form bauxite