Even non-plastics such as quartz or zirconium di oxide can be converted into fictile masses through prolonged fine grinding. But they have no cohesion and flow like casting slip. There is a connection between the lamellar shape and plasticity. And hence it is considered that the lamellar form of clay particles to be the most important cause of its plasticity. There is a difference in behaviour of lamellar and granular materials. This can be explained by comparing them with a pack of cards and a hand full of balls thrown on to a table. The cards maintain some sort of contact with one another whereas the balls are scattered irregularly. Similarly a plastic mass made from lamellar clay particles does not fall apart on being kneaded, whereas a mass of quartz particles develops cracks on all sides.
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