A base silver coin of Annam, having on one side inscriptions surrounding a sun, and on the reverse the figure of a dragon. It was introduced during the reign of the Emperor Minh Mang (1820-1842), and was current for a Piastre, or double the value of the Quau (q.v.). See Fonrobert, Die Jules Fonrobert'sche Sammlung uberseeischer Munzen, 1878, pp. (2109-11, 2115-17). There are both dated and undated varieties. The word Tambac-tron means "round silver"