Histamenon was the name given to the gold Byzantine solidus when the slightly lighter tetarteron was introduced in the 960s. To distinguish the two, the histamenon was changed in form from the original solidus, becoming wider and thinner, as well as concave (scyphate) in form. Later usually shortened to stamenon, it was discontinued after 1092. In the 12th and 13th centuries, the name stamenon came to be applied to the concave billon and copper trachea coins.
Histamenon of Emperor Constantine VIII (r. 1025–1028)
Histamenon of Emperor Isaac I Komnenos (r. 1057–1059), with its by then characteristic concave form
An example of the greatly debased later histamena: an electrum coin of the first years of Emperor Alexios I Komnenos (r. 1081–1118).
The tetarteron was a Byzantine term applied to two different coins, one gold circulating from the 960s to 1092 in parallel to the histamenon, and one copper used from 1092 to the second half of the 13th century.
Gold tetarteron of the sole rule of Empress Theodora (r. 1055–1056).
Copper tetarteron of Emperor Manuel I Komnenos (r. 1143–1180).