Clay proto-cuneiform tablet with early pictographic writing, end of the 4th millennium B.C.

Clay or stone tablets with cuneiform writing. Most common are pillow-shaped clay tablets (one side rounded, the other side flat), square or rectangular, sometimes round. They typically range from 4 x 5 cm to 20 x 30 cm in size. They sometimes have a casing (often fragmentary), sealed. They are usually sun-dried and must be handled with extreme care. If not stored under controlled humidity, they may disintegrate (optimum relative humidity: 45-50%). For identification, they should be photographed under raking light coming from the upper left.