Tetartemorion

Euromus, a minor Karian city near Mylasa, issued coins at a time when fractional silver coinage served the granular demands of local market exchange — a tetartemorion being one quarter of an obol, itself one sixth of a drachm. At 0.21g, this is about as small as ancient hand-struck coinage gets without losing functional coherence entirely.

The city later became more prominent under Macedonian and then Seleukid influence, but these early Karian issues predate that political absorption entirely.