How old is that silver in your hand?

An article that made me go hmmm. Bolivian silver was going to China back in the 1500's. That's where all the silver (and gold) is going now, too.
http://www.sciencenews.org/view/generic/id/346607/title/Mexican_silver_made_it_into_English_coins
http://www.sciencenews.org/view/generic/id/346607/title/Mexican_silver_made_it_into_English_coins