Valuable deposits ranging in composition from high-grade boehmitic or monohydrate bauxite to rather pure kaolin clay occur along an unconformity between Permian and Paleocene-Eocene beds in the Kattha area. Investigations by microscopic, X-ray, and differential thermal analysis methods reveal that boehmite is the principal bauxite mineral in the deposits and only a small amount of gibbsite was found. All deposits contain some kaolinite, and this mineral is ordinarily most abundant in the upper parts of the bauxite. Kaolinite is also more abundant in some deposits than in others, and some of the more clayey ones contain few other minerals. Natroalunite and possibly alunite occur in the upper parts of some deposits, and the other minor impurities include rutile, calcite, hematite, and quartz. Alumina contents of the deposits range from 35 to 73 percent and silica ranges from 8 to 50 percent.

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