Tetarteron - Alexios I Komnenos Thessalonica, patriarchal cross type

The tetarteron as a bronze denomination was itself a creation of Alexios I's sweeping monetary reform of 1092, which overhauled a currency system so debased it had become functionally useless. Prior to the reform, the gold nomisma had lost roughly 90% of its precious metal content over the preceding century. The new tiered system introduced the electrum aspron trachy, billon trachy, and this small bronze denomination to handle low-value transactions.

The Thessalonica mint operated as a secondary production center, and its output of this type is considerably scarcer than Constantinople's equivalent issues.