GEOLOGICAL DISTRIBUTION
The European bauxite deposits are in folded sedimentary rocks, mainly of Cretaceous age. In the United States bauxite deposits are surficial and have resulted from the alteration of either sedimentary kaolin (aluminum silicate) or kaolin derived from the weathering of syenite or of dolomitic limestones. In the tropical fields, which have as yet been little exploited and are in fact little known, the bauxites seemingly are surficial deposits derived from the alteration of feldspathic rocks.