Characterization for industrial applications of clays from Lembo deposit, Mount Bana (Cameroon) P. PIALY 1,2 , C. NKOUMBOU 2,4, *, F. VILLIE ´ RAS 4 , A. RAZAFITIANAMAHARAVO 4 , O. BARRES 4 , M. PELLETIER 4 , G. OLLIVIER 4 , I. BIHANNIC 4 , D. NJOPWOUO 1 , J. YVON 4 AND J-.P. BONNET 3 1 LaboratoiredePhysico-chimiedesMate ´riauxMine ´raux,De ´partementdeChimieInorganique,Faculte ´ desSciences, B.P.812Yaounde ´,Cameroon, 2 EquipedeGe ´ologieEconomiqueetEnvironnementale,De ´partementdesSciencesdela Terre,Faculte ´desSciences,B.P.812Yaounde ´,Cameroon, 3 Grouped’EtudedesMate ´riauxHe ´te ´roge `nes,ENSCI,47a ` 73, avenue Albert Thomas, 87065 Limoges Cedex, France, and 4 LaboratoireEnvironnementetMine ´ralurgie,Nancy- Universite ´, CNRS, 15 Avenue du Charmois, BP 40 F- 54501 Vandoeuvre-le `s-Nancy, France (Received 24 April 2007; revised 19 March 2008) ABSTRACT: The Lembo clay deposit occurs on orthogneiss, but it also comprises clays with litho- relicts of volcanic rocks. In this study, ten samples from two sites were investigated. The mineralogical compositions consisted of kaolinite + halloysite + illite + quartz + hematite + anatase Ô rutile Ô orthoclase Ô sanidine Ô magnetite Ô maghemite Ô goethite Ô Ba-Al-Fe-phosphates Ô carbonates Ô sulphates. Kaolinite-halloysite and quartz are the prevailing minerals. Some volcanic- derived clays contain Fe-rich kaolinite-halloysite (9.614.1 wt.% Fe 2 O 3 ). The chemical compositions, colours and specific surface area (SSA) measurements reveal two groups of clays: one with a positive whiteness index (IB), small SSA and small Fe content, and the other showing a large SSA, negative IB and relatively large Fe contents. The compositions of the first group are close to those of clays from the Mayouom deposit (Cameroon), and from some European commercial kaolins used in ceramics. Relatively Fe-rich clay materials may conform to most formulations of earthen bricks. As a whole, the Lembo clay deposit comprises various compositions of kaolinitic clays, which may yield the opportunity for extensive application in ceramics. KEYWORDS: clay materials, characterization, industrial applications, Cameroon. Clays have been used in many industrial applica- tions for a very long time (Caille `re et al., 1989; Yvon et al., 1990, 2002). In developed countries, industrial uses of clays cover many applications such as coating and filler pigment for paper; filler for paint, rubber and plastics; formulation additives in food, insecticides, cosmetics, pharmaceutics, fertilizers and soil correctors, and as a major component in ceramics, drilling fluids and geochemical barriers. However, in developing countries such as Cameroon, most clay-based goods are imported due to poor technological development (Nkoumbou et al., 2006). A few studies of clay materials in Cameroon have focussed on physicochemical characteristics and the beneficiation of kaolinite, illite, palygorskite and smectites (Njopwouo, 1984; Njopwouo et al., 1987, 1988; Kamga et al. , 2001; Elimbi & Njopwouo, 2002; Nguetnkam, 2004; Njoya et al., 2006; Nguetnkam et al., 2007), or on physico- * E-mail: charles.nkoumbou@ensg.inpl-nancy.fr DOI: 10.1180/claymin.2008.043.3.07 ClayMinerals, (2008) 43, 415–435 # 2008 The Mineralogical Society