Clay materials for ceramic tiles from the Sassuolo District (northern Apennines, Italy). Geology, composition and technological properties

In the Sassuolo area northern Italy. there is the largest tilemaking district in the world, which has practically served over the past years as an industrial scale laboratory for assessing the technological properties of clays and their suitability for the production of wall and floor tiles. The local clays are recovered from different geological units and distinguished in two principal types, with clearly differentiated compositions and technological properties: ''marly clays'' and ''red shales''. These local clays, which 20 years ago constituted the sole mineral resource of the Sassuolo District, now supply only 40% of the demand. This trend is largely connected with both process innovation wet grinding, fast firing, etc.. and product changes from red to white bodies.. Overall, approximately 2 million tpa of clay materials are used in coloured bodies: marly clays for wall tiles majolica, ''birapida'', ''monoporosa''. and red shales for both floor tiles glazed red stoneware. and wall tiles ''monoporosa''..