Do we know how long after minting an ancient Roman coin could be used? For example, was a Hadrian denarius struck in ~100AD still able to be spent in ~300AD, even though the denarius had been phased out of minting? Was this illegal, or culturally discouraged? Would a coin that old have been treated as an antique or artifact at that time, similar to how no one would spend a silver dollar today? It seems inevitable that they fell out of use once they were no longer minted, but just curious if much is known about this.