Tetarteron - Manuel I Komnenos Thessalonica

Manuel I ruled for 37 years and kept the Byzantine mint at Thessalonica busy supplying the western provinces and the Balkans, where his campaigns against the Normans and the Hungarians demanded a steady local currency. The Thessalonian issues of his reign are distinguishable from Constantinople production by subtle die differences catalogued under the BMC groupings, and collectors frequently conflate the two without close examination.

The tetarteron by this period had shed its original role as a fractional gold denomination — that function collapsed generations earlier — and survived purely as a copper fiduciary piece. Its continued use of the old name was administrative habit, nothing more.