Tetarteron - Alexios I Komnenos Thessalonica

The tetarteron as a bronze denomination was itself a product of Alexios I's sweeping monetary reform of 1092, which overhauled a Byzantine coinage system that had degraded catastrophically over the preceding decades — the gold nomisma had collapsed in fineness from near-pure to roughly 8 karats by the 1080s. The reform introduced a rigid four-metal hierarchy, and the bronze tetarteron occupied its lowest rung.

Thessalonica was the empire's second city and its mint operated with some autonomy, producing tetartera distinguishable from Constantinople issues by subtle fabric and die differences catalogued under the Dumbarton Oaks corpus.