This study aims to find alternatives to some overexploited deposits in the north of Tunisia. The clays of the Sidi Khalif formation, of Uppermost Jurassic to Lower Cretaceous age, seem suitable to support this strategy, due to their abundance. In terms of mineralogy, they can be divided into two distinct groups, related to their palaeogeographic and eustatic contexts. The clays of the Sidi Khalif formation from Jebel Houareb (JH) and Jebel Meloussi (JM) are richer in clay minerals, while those of Jebel Rhouis (JR) and Jebel Boudinar (JB) zones are dolomite-rich. The compositional differences between the two groups influenced their technological behaviour in production of ceramic tiles. Upon firing, forsterite and gehlenite crystallized in the carbonate-rich JR and JB clays, whereas mullite formed in the JH and JM clays. Concerning their ceramic properties, the tiles made from JR or JB clays showed low bending strength and high water absorption. For JH and JM, the tiles had slightly greater mechanical resistance, but exhibited considerable linear shrinkage. These defects were partially corrected by introducing new formulations based on the same clays and by altering the firing cycles (HM1, HM2, RB1 and RB2). With these modifications, “Porcelanico” and “Monoporosa” technologically conforming tiles were obtained from HM2 and RB2 formulations, respectively.

The Yaylayolu kaolin deposit is situated in the vicinity of Tavşanlı, Kütahya, western Turkey. Mineral identification and characterization studies were conducted using powder X-ray diffraction (XRD), differential thermal analyses (DTA), scanning electron microscopy with an energy dispersive X-ray spectrometer (SEM-EDX), X-ray fluorescence (XRF) and Fourier transform infrared spectroscopy (FTIR) techniques. The degree of crystallinity, Hinckley's index (HI) and the Stoch index (SI) values were determined for kaolinite from the deposit.

Five representative samples from the kaolin deposit were used for ceramic technological tests. Particle size distribution, pH value, loss on ignition, A12O3, Fe2O3 and TiO2 contents were determined, drying shrinkage, firing shrinkage, dry bend strength, fired bend strength, water absorption, pfefferkorn plasticity index, whiteness of the fired and unfired samples (L* value) and bulk density were measured. The kaolin was found to be suitable for making white cement and wall tiles, floor tiles, and tableware items which are shaped by dry pressing and extrusion.

Elemental behaviour, during the process of weathering of glazed sekishu roof-tiles affected by Lecidea s.lat. sp. (a crustose lichen), was investigated using optical and fluorescence microscopy, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy. Sekishu roof tiles have an opaque reddish brown glaze on their surfaces which consist of an alkali feldspar-type X-ray amorphous glass recrystallized at 1200°C. Optical and fluorescence microscopy revealed the presence of corrosion pits (at a depth of ∼50 μm) at the lichen-glaze interface. Elemental mapping by FE-SEM identified the concentrations of Ti and Fe in the section of the glazed tile analysed. The behaviour of C was correlated with those elements, suggesting the possibility of biomineralization.

White clayey geomaterials were collected from northeast of the Nefza region (northern Tunisia). These deposits belong to the Mio-Pliocene molassic basins (basin of Tamra-Sidi Dris, Boukhchiba) and Oligocene Numidien in the area of El Aouinet. Analysis by X-ray diffraction showed associations of halloysite and kaolinite (Tamra), kaolinite and illite (Aouinet zone) and mixed layers, kaolinite and feldspars (Boukhchiba zone). Semi-industrial processed bricks showed promising characteristics and were visibly free of defects. Ceramic tiles had a bending strength that met the required standards but water absorption was somewhat high. So, to achieve higher quality, optimisation needs to be carried out in the formulation of batches or in the processing conditions. Finally, the incorporation in whitish sanitary-ware glaze formulations generated smooth coating layers that showed the required strong brightness and were free of defects.

This paper explores the development of tile-stamping in the period a.d. 100–50 by the Gloucester and Cirencester civic authorities, and by private tile-makers in Gloucestershire, and the territorial divisions between them. It argues that builders’ merchants were used in tile distribution and building reclamation and, inter alia, identifies Hucclecote villa as such a site. It proposes that Gloucester tiles stamped just RPG were issued annually and were used for commercial purposes while tiles with magistrates’ names were issued as required, but only for use on public buildings. The evidence suggests that these stamps were subsequently extensively curated. This paper adds nearly 200 new stamps to the existing catalogues and proposes significant revisions to the magistrate dies as a result.