The probable composition of a weathered, blue-green glaze on a ground quartz bead was reconstructed. The bead was excavated from Operation 5 at Tell es-Sweyhat, Syria, in 1991 and is dated to the last quarter of the third millennium B.C. Special sample handling was required by the poor state of preservation of the glaze. Microprobe analyses and replicate melts showed that the composition was 60% SiO2, 20% CuO and 20% flux, probably as soda, potassia or a combination. This composition is unusual for ancient glasses and glazes because of its high copper oxide content, which may indicate a link with copper or malachite technology. Very few glass and glaze compositions are known from the third millennium B.C., and none of these has such a high copper concentration, nor are there examples reported from the mid-second millennium B.C. with one exception of glazed tiles from Kerma in Sudan. This rare and unusual composition suggests that there may have been several paths to the development of glasses and glazes. Some of these paths were successful, and some others, as this one, did not continue and were “dead-end” technologies.