AB ST R ACT : The empirical application of muds for therapeutic purposes is widely known. This is called pelotherapy and consists of the local or generalized application of a mixture of a solid phase and a liquid phase (peloid) for the recovery of arthro-rheumatic issues, bone-muscle traumatic damage and dermatological pathologies. During the time of mixing (maturation process) the mud is progressively colonized by thermophilic microorganisms that contribute to improvements in the peloid quality and endow the mud with organic substances. Several studies report diatoms as the main agent of thermal muds capable of producing anti-inflammatory sulphoglycolipid which renders the mud suitable for this use. The effect of the temperature is also considered important for therapeutic purposes.Recent studies assessed physical, chemical and technological properties of some peloids in use at spa centres. Some maturation surveys have also been performed in recent years. The need for quality criteria establishment and certification of clayey products intended to be used currently is evident, especially for peloids which have therapeutic action. Consequently, this study aims at the compilation and analysis of some characteristics of peloids from the literature in order to contribute to a major database that allows the establishment of regulations and quality criteria for suitable applications of peloids.

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AB ST R ACT : The unique properties of clays make them suitable for a large number of applications. Among the procedures that can be used to characterize clayey materials, the assessment of the abrasion and the abrasiveness index can be employed to predict the mechanical behaviour of clay samples. However, only a limited number of references to these testing procedures are available in the literature. Several Portuguese clayey samples were collected and the <63 mm fraction was analysed. The main clay minerals present are kaolinite, illite and smectite. The abrasiveness index depends on the granulometric and mineralogical compositions. A lower abrasiveness is induced by the presence of a high abundance of the <2 mm fraction, small mean particle size and a large phyllosilicate content . Kaolinite and illite show good correlation with the abrasiveness index, while smectite decreases abrasion.

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