Characterization of Portuguese geological materials to be used in medical hydrology

In order to be used in therapeutics, geological materials must comply with a number of specifications. In particular, clays used as pharmaceutical raw materials must be safe. As a product to be manipulated during the manufacture of drug dosage forms, they are also required to satisfy a number of technological features, including flowability and texture. With these premises, this work aimed to characterize mineralogical, textural and technical properties of Portuguese clayey raw materials belonging to well known formations (from Upper Jurassic to Miocene in age). Some of these materials are used in particular beaches for their therapeutic properties. The present study showed that mineralogical and chemical compositions of the samples allow for their safe therapeutic application. Nevertheless, in some particular samples, it could be necessary to reduce the quartz content and coarse particles before use. Bulk samples showed better flow patterns than the < 63-μm samples. For that, the use of bulk samples is preferred over separated samples. The most suitable materials for medical hydrology applications were those belonging to Freixial, Aveiro, Barracão, Luz, Xabregas and Serra de Dentro Bentonite formations.