The end of 11th century witnessed the full collapse of the Byzantine monetary system, which had remained stable since the 3d century AD. The two gold coins, the tetarteron and the histamenon had suffered a series of debasements until in 1081 their gold content was so low they could barely justify their names. At the same time, the minting of silver coins had almost stopped, while the copper folles were struck sparingly. In 1092 he Emperor Alexios I Komnenos took drastic measures and reformed the Byzantine monetary system for the first time. He issued a completely new series of scyphate (cupped shaped) coins: the golden hyperpyron and the aspron trachy (white, uneven) made of electron (1/3 of a hyperpyron in value), and the aspron trachy made of billon (1/48 of a hyperpyron). The histamenon, the tetarteron and the miliaresion of the previous period continued to circulate. The tetarteron, however, was changed into a small, thick copper coin in order to create a smaller denomination coin. Like the folles of former times, it was in turn to disappear: the latter tetartera, extremely small in size, circulated in the days of Manuel Komnenos (1143-1180). The new system ran through the 12th century, with one addition, that of the half tetarteron in the reign of John II (1118-43). The two aspra trachea, however, were significantly debased. The trachy made of billon was reduced by the end of the century to the 1/184! of the value of the hyperpyron (thanks to a progressive reduction in the silver content of its alloy which at the beginning was at least 60%), while that made of electrum was debased in the reign of Isaac II (1185-95) to such a degree that it did not survived through to the Late Byzantine era.