Mineralogical evaluation and industrial applications of the Triassic clay deposits, Southern Tunisia H. Baccour a, ⁎ , M. Medhioub b , F. Jamoussi c , T. Mhiri a , A. Daoud a a Laboratoire de l'Etat Solide, Faculté des Sciences de Sfax 3018, Sfax, Tunisia b Laboratoire Géoressources, Faculté des Sciences de Sfax 3018, Sfax, Tunisia c Laboratoire Géoressources, CERTE, Bp.273, Soliman, 8020, Tunisia ARTICLE DATA ABSTRACT Article history: Received 13 September 2006 Received in revised form 21 February 2008 Accepted 26 February 2008 This study deals with the mineralogical and thermal analysis of Triassic clays in the south- Eastern Tunisia (Medenine area) in order to use them in the faience ceramic. That is why the study had recourse to several quantitative and qualitative research instruments: chemical analysis, mineralogical study, thermal analyses and analyses of geotechnical traits. The data collected from these techniques show that illite and kaolinite are the major clay phases. The accessory minerals detected in powdered rock are; quartz, dolomite and hematite. Geotechnical characterization was carried out on the three representative mixtures of Triassic clay samples. Each mixture is fired at three different temperatures 850,900 and 950 °C. Firing characteristics (shrinkage, water absorption, and mechanical resistance to the inflection) were measured and the neomineralization processes were investigated principally by X-ray diffraction. At the end of this study, one can affirm that these clays have qualities necessary for the manufacture of faience ceramic and earthenware production. © 2008 Elsevier Inc. All rights reserved. Keywords: Tunisian clay Kaolinite Faience ceramic Thermal analysis Firing 1. Introduction Clays are used as raw materials in many industrial fields (ceramics, paper, paint, petroleum industry, clarification of various effluents, catalysis...) [1]. Their applications are tightly dependent upon their structure, composition, and physical attributes [2]. The knowledge of these characteristics can help for best exploitation and eventually may open up new areas of application. Clay deposits areas have a high economic potential, and soil mineralogical composition, plasticity and porosity are fundamental properties for industrial application. Clays are widely used in the manufacture of many traditional ceramics. Kaolinite illite is the most widely used clay mixture in the ceramic industry [3]. A potential source of clay materials for ceramic industry was discovered in Southeastern Tunisia, namely extensive Triassic sedimentary clay deposits, as clays from this region are rich in illite and kaolinite, and widely used as raw materials for red brick by the local ceramic industry. In the present study, a detailed characterization of these clays is reported including their possible application in faience ceramics production. The Tunisian production of ceramic faience has presented a rapid growth since 2000 (Fig. 1) [4]; in addition, the Tunisian production can grow still more due to the high internal demand and opportunities for growth of exports. Although there is a great commercial interest in ceramic faience, very little research has been conducted in Tunisia on developing ceramic faience. The assessment of the possible applications of the Triassic clays in the ceramic faience was carried out on the basis of chemical, mineralogical and technological results. The geology of the Triassic clays in Southeastern Tunisia has been reported by Jamoussi in 2001 [5], in order to enhance and extend their applications. Within MATERIALS CHARACTERIZATION 59 (2008) 1613 – 1622 ⁎ Corresponding author. E-mail address: hajerbaccour@yahoo.fr (H. Baccour). 1044-5803/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.matchar.2008.02.008