Histamenon (Greek:ἱστάμενον [νόμισμα],histámenon [nómisma]lit. 'standardcoin') was the name given to the goldByzantinesolidus when the slightly lightertetarteron was introduced in the 960s. To distinguish the two, thehistamenon was changed in form from the originalsolidus, becoming wider and thinner, as well as concave (scyphate) in form. Later usually shortened tostamenon (Greek:στάμενον), it was discontinued after 1092. In the 12th and 13th centuries, the namestamenon came to be applied to the concavebillon andcoppertrachea coins.

Ever since EmperorConstantine I (r. 306–337) introduced it in 309, the Byzantine Empire's main coinage had been the high-qualitysolidus ornomisma, which had remained standard in weight (4.55 grams) andgold content (24 carats) through the centuries.^[1][2] EmperorNikephoros II Phokas (r. 963–969), however, introduced a new coin, the[nomisma] tetarteron ("quarter [coin]") which was 2 carats (i.e. about¹⁄₁₂, despite its name) lighter than the originalnomisma. The latter now became known as thehistamenon, from the Greek verbἵστημι, "to stand up", implying that these followed the traditional standard.[3]^[4][5] The reasons for this change are not clear; Byzantine chroniclers, however, suggest fiscal motives, reporting that Nikephoros collected the taxes as before in thehistamenon while paying back with thetetarteron, which was officially rated as equal in value to the full-weight coin.^[3]

Initially, the two coins were virtually indistinguishable except in weight. During the later reign ofBasil II (r. 976–1025), thetetarteron began to be minted in a thicker and smaller form, while thehistamenon became correspondingly thinner and wider. Only during the sole rule ofConstantine VIII (r. 1025–1028) did the two coins become iconographically distinct as well.[6]^[7] By the mid-11th century, thetetarteron measured 18 mm wide and its weight apparently standardized at 3.98 grams, i.e. three carats less than thehistamenon orstamenon (a name first attested in 1030), which now measured 25 mm in diameter (as opposed to 20 mm for the originalsolidus). In addition, underMichael IV the Paphlagonian (r. 1034–1041), it began to be minted in a slightly concave (scyphate) form, possibly to increase the thin coin's strength and to make it less easily bent. Flat coins were still struck at times, but scyphate ones came to predominate fromConstantine IX (r. 1042–1055) on and became standard underIsaac I Komnenos (r. 1057–1059). These concave coins were known ashistamena trachea or simplytrachea (τραχέα, "rough, uneven") from their shape.[8]^[9][10][11]

Starting with Michael IV, who was a former money lender, the gold content began to be increasingly lowered and the coins debased. After a period of relative stability inc. 1055–1070, the gold content declined dramatically in the disastrous 1070s and 1080s. Themichaelata ofMichael VII Doukas (r. 1071–1078) still contained some 16 carats of gold, but by the time ofAlexios I Komnenos (r. 1081–1118), thenomismata struck contained almost no gold at all.[11]^[12][13] Thus, in 1092, Alexios I carried out a comprehensive monetary reform, replacing among others the debased gold coins, both thehistamenon and thetetarteron, with a new high-quality gold issue, thehyperpyron.^[14][15]

Henceforth, and for the duration of the Komnenian monetary system (12th–13th centuries), the termstamenon, due to its association with scyphate coins, came to be applied as a blanket term to the similarly concave billon and copper coins (trachea) issued by the Byzantine Empire.^[16][17]