Ariminum was Roman colony founded 368 BCE. Gorini 2010 gives a full study to the coinage and places its first aes grave series in the period from 264-241 BCE i.e. the First Punic War. He also says that the series is based on a pound of 380g. That’s MUCH heavier than the Roman pound (whatever we think it was, probably c. 325 plus or minus 5). I thought, that can’t be right, so I re-looked at the data.
I might be inclined to suggest a target weight for the Ariminum pound c. 355-360, still heavier than the Roman, but not so extreme.
Why would a colony choose to use a heavier measure? Accident? Intent? Why use a base 10 instead of base 12 fraction system?!
This plate from Marchi 1839 suggests that there was a still larger denomination, unrecorded by Gorini 2010 and other recent commentators. Is that a horse head? Inspired by RRC 13/1?