Bauxite deposits in Suriname and Demerara (British Guiana)

On the basis of the morphology and stratigraphic positions, the bauxite deposits in Suriname and Demerara (British Guiana) were divided into four main groups, namely: 1. Plateau type bauxite, 2. High-level type bauxite, 3. Medium-level type bauxite, 4. Low-level type bauxite. The age of these deposits is as follows: Plateau type bauxite .................................... Pre-Tertiary Low-level type bauxite ................................ Middle- to Lower-Tertiary High-level and Medium-level type bauxite .... Pleistocene These three main periods of bauxitization have led to the formation of fossil bauxite. After these main periods the bauxitization process, however, has not come to a standstill. It continues even at the present time, although less intensively, so that young, sub-recent to recent bauxite is also found. In all bauxite deposits a layer of kaolin underlies the bauxite. In the case of the Plateau type and the Low-level type this kaolin has been derived from solid rock. The kaolin situated below the bauxite of High-level and Medium-level type, is a sedimentary kaolin. In the transition zone between the kaolin and the bauxite, resorption of kaolinite and crystallization of gibbsite is observed. The growth of the bauxite, at the expense of the soil cover clays has been well observed at Onverdacht, where Coropina clay and sub-recent to recent swamp clays (which clays mainly consists of illite) are subject to recent bauxitization after a preceding kaolinization. One can observe the same bauxitization in the transition zone of the bauxite and the soil cover at Mackenzie (Demerara), where this process also takes place in the kaolin clay of the Zandery formation. The chief mineral of the bauxite is gibbsite. Boehmite is also found but in small quantities varying with the age of the type of deposit. The main constituent of the ferrite is hematite, which is an alteration product of goethite. Goethite is found to a much smaller extent. It is not probable that unknown bauxite deposits of the Plateau type and High-level type still exists in Suriname. This is in contrast to the Mediu-level type deposits. All of these deposits have most probably not yet been found. Low-level type bauxite is only seen in Demerara. There are indications, in the form of large and small boulders of bauxite and ferrite in the Zanderij formation, which leads us to believe that this type also occurs in Suriname.