Mineralogical, geochemical, and sedimentological characteristics of clay deposits from central Uganda and their applications

Abstract

In Uganda, Precambrian rocks have undergone extensive weathering and erosion, and are locally altered to form considerable clay deposits. We have studied the geochemical, mineralogical, and sedimentological characteristics of clay deposits from central Uganda to determine their composition, source rocks, deposition, and possible use in local industry. Samples were collected from the Kajjansi, Kitiko, Masooli, and Ntawo deposits (near Kampala), all of which are currently used for both industrial and traditional brick, tile, and pottery manufacture. The deposits are widely scattered individual basins, with clays deposited under lacustrine and alluvial environmental conditions, and were all found to belong to the sedimentary group. The clays are composed of silt–sand fractions and predominantly consist of kaolinite and have a relatively high Fe 2O 3 content. The studied deposits are chemically homogeneous, except for the samples richer in sand fraction, which have higher SiO 2 and K 2O values. The chemistry of the studied samples, compared to European clays, shows that they need elaborate treatment to render them suitable for ceramics production. An analysis of the chemical and mineralogical composition of the clays has demonstrated that, taken as a whole, they possess characteristics satisfactory for brick production.