Histamenon

Histamenon (Greek: νόμισμα ἱστάμενον, "standard coin") 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 (Greek: στάμενον), 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.

Ever since Emperor Constantine I (r. 306–337) introduced it in 309, the Byzantine Empire's main coinage had been the high-quality solidus or nomisma, which had remained standard in weight (4.55 grams) and gold content (24 carats) through the centuries. The Byzantine emperor Nikephoros II Phokas (r. 963–969), however, introduced a new coin, the [nomisma] tetarteron ("quarter [coin]") which was 2 carats (i.e. about ¹⁄₁₂, despite its name) lighter than the original nomisma. The latter now became known as the histamenon, from the Greek verb ἵστημι, "to stand up", implying that these followed the traditional standard. The reasons for this change are not clear; Byzantine chroniclers, however, suggest fiscal motives, reporting that Nikephoros collected the taxes as before in the histamenon while paying back with the tetarteron, which was officially rated as equal in value to the full-weight coin.

Initially, the two coins were virtually indistinguishable except in weight. During the later reign of Basil II (r. 976–1025), the tetarteron began to be minted in a thicker and smaller form, while the histamenon became correspondingly thinner and wider. Only during the sole rule of Constantine VIII (r. 1025–1028), however, did the two coins become iconographically distinct as well. By the mid-11th century, the tetarteron measured 18 mm wide and its weight apparently standardized at 3.98 grams, i.e. three carats less than the histamenon or stamenon (a name first attested in 1030), which now measured 25 mm in diameter (as opposed to 20 mm for the original solidus). In addition, under Michael 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 from Constantine IX (r. 1042–1055) on and became standard under Isaac I Komnenos (r. 1057–1059). These concave coins were known as histamena trachea or simply trachea (τραχέα, "rough, uneven") from their shape.

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