Sherds from the Chalcolithic levels at Teleilat Ghassul show evidence of a considerable degree of sophistication in pottery technology and design. The bodies are almost certainly made from a siliceous illitic clay which contained some calcium carbonate, and was obtained locally. Some unusual, yet common, sherds are composed of highly vitrified black bodies with a surface wash of a refractory white clay. These sherds indicate the production of one of the earliest known totally vitrified ceramic fabrics. The latter sherds have been examined in some detail by chemical, thermal and x-ray analysis, and optical and scanning electron microscopy.