Weight is 2.25 g, about 20-21 mm diameter. Price was $6 so I'm not out for much. I looked it up online and can't find an exact match. Here's the 1750 Papal States quattrino on Numista. The inscriptions on mine are a little different. I think mine says: ob: BENE XIV P rev: PORTA SANCTA (holy door) I think the door is a reference to the Jubilee year of 1750. Benedict XIV was pope from 1740-58 The lack of an explicitly stated denomination (it's a little heavier than the 2.1 g I would expect for a quattrino) and date (papal year or AD) are bugging me. I wonder if it could be a contemporary privately issued copper token. The version of the Papal Arms looks like it might be a regional issue from Gubbio. Krause lists a 1750 Quattrino from Gubbio as a "holy year issue" with no image. I can't find it on Numista for that year at all. Any suggestions welcomed.