Lanefan
Victoria Rules
If the setting has creatures like Dwarves in it, this would get caught and called out real fast.Also there is a sort of weird thing to think about is that the Romans constantly changed the purity of the silver in their coins as a way to inflate their value.

And if the purity was uncertain, you wouldn't know that metallic value until the coins had been melted down...which probably costs money to have done for you unless you've a metalsmith in the party and access to a forge oven.So that horde of coins could simply not be spent as money, only sold as for its metallic value, and only then in a larger city, probably capital of a kingdom.