With the exception of a few 6th-century ceremonial issues, silver coins were not used in the late Roman/early Byzantine monetary system (see Byzantine coinage), chiefly because of the great fluctuation of its price relative to gold. Only under Emperor Heraclius (r. 610–641), in 615, were new silver coins minted to cover the needs of the war with Sassanid Persia. The material for these coins came chiefly from the confiscation of church plate. They were named after their weight of six grammata (6.84 grams), and probably valued at 12 to the gold solidus. The coin remained in regular issue under Heraclius's successor Constans II (r. 641–668), from whose reign many specimens survive, but becomes rarer for Constantine IV (r. 668–685), and thereafter seems to have been only occasionally minted as a ceremonial coin until abandoned entirely under Anastasios II (r. 713–715). In 720, however, Emperor Leo III the Isaurian (r. 717–741) issued a new silver coin, the miliaresion.