FROM SHIFTING SILT TO SOLID STONE - THE MANUFACTURE OF SYNTHETIC BASALT IN ANCIENT MESOPOTAMIA

Slabs and fragments of gray-black vesicular ''rock,'' superficially re sembling natural basalt but distinctive in chemistry and mineralogy, w ere excavated at the second-millennium B.C. Mesopotamian city of Mashk an-shapir, about 80 kilometers south of Baghdad, iraq. Most of this ma terial appears to have been deliberately manufactured by the melting a nd slow cooling of local alluvial silts. The high temperatures (about 1200 degrees C) required and the large volume of material processed in dicate an industry in which lithic materials were manufactured (''synt hetic basalt'') for grinding grain and construction.