Soil composed of the dust from igneous rocks mixed with water. Soft and sticky, it can be moulded or cut into shapes which are hardened on exposure to heat. The first known form of handwriting, cuneiform script, was on tablets of clay and developed in Mesopotamia c.3000 bc. Clay has been used for many purposes including the manufacture of seals, bricks, tiles, jars, and jugs. In sculpture it has been used to make models for larger pieces, for moulds of works to be cast in metal, or as sculpture in its own right. Clay is also the main ingredient for all ceramic bodies.