hyperpyron

thumb|250px|right|Hyperpyron of Emperor Manuel I Komnenos (r. 1143–1180), showing its typical [[scyphate (cup-shaped) form.]]The hyperpyron (, nómisma hypérpyron ) was a Byzantine coin in use during the late Middle Ages, replacing the solidus as the Byzantine Empire's standard gold coinage in the 11th century. It was introduced by emperor Alexios I Komnenos.

==History== The traditional gold currency of the Byzantine Empire had been the solidus or nomisma, whose gold content had remained steady at 24 carats for seven centuries and was consequently highly prized. From the 1030s, however, the coin was increasingly debased, until in the 1080s, following the military disasters and civil wars of the previous decade, its gold content was reduced to almost zero. Consequently, in 1092, Emperor Alexios I Komnenos ( 1081–1118) undertook a drastic overhaul of the Byzantine coinage system and introduced a new gold coin, the hyperpyron (meaning "super-refined"). This was of the same standard weight (4.45 grams) as the solidus, but only 20.5 carat purity (0.854 fineness) instead of the standard 24 carat, resulting in a reduced gold content of only 4.1 grams instead of 4.8 grams. The lower purity was due to melting down and inclusion of earlier debased coins.