MACEDON, Chalkidian League. Olynthos. Circa 400 BC. Trihemiobol (Silver, 9 mm, 0.38 g, 1 h), this coin is commonly ascribed to a city named Trieros, or a tribe called the Trieres, but see the note below for the attribution and the denomination. Laureate head of Apollo to left; border of dots. Rev. Τ-Ρ/Ι-Η Laurel branch within a plain square linear border; all within a shallow incuse square. HGC 3, I, 507. Cf. Psoma, Monnaies, p. 103, 6472. Robinson-Clement Type 2 ( Trieros ). SNG Copenhagen 821-822 ( Trierus in Thrace ). Attractive and of lovely style. Minor roughness and marks, otherwise, nearly extremely fine.

From the "Collection sans Pareille" of Ancient Greek Fractions.

While this is a small coin, it has a large number of mysteries that surround it! The first concerns its mint: for long it was thought to have been issued in an otherwise unknown Macedonian city named Trieros, but this city seems not to exist! In fact, the letters on the reverse, ΤΡΙΗ, indicate a denomination, generally believed to be a trihemiobol ; furthermore, the coin has been re-attributed to Olynthos, capital of the Chalkidian League (especially since coins of this type have been found there - fractions tend not to travel far from their mint). This brings us to a second problem: this coin weighs 0.38 g, and all the other known examples are around this weight too; but what kind of standard results in a coin of one-and-a-half obols weighing only 0.38 g?? The only possible explanation must be that this coin was officially over-valued for local/regional use; since it had a much greater value at home it would not circulate elsewhere. Do see Psoma's article for an exhaustive and correct explanation.