If it's someone's wallet, sure...I'd turn it in, because that's the right thing to do, and it's what I'd want someone to do for me. But a long-lost treasure, there is no way I'd tell anyone at all about that. Collecting and using it would be a challenge for sure, but telling and expecting some kind of reward for being a good goy betrays a complete lack of sense about today's world. It would have been better to just leave it there untouched and keep it in the back of his mind in case he had a use for it someday.