Very little gold that is mined gets lost. People always try to recover it if has been used in dental work, electronics etc. .....So just about all the gold ever mined is still around
Silver does get discarded while some gets recovered. So silver constantly has to be mined for its industrial uses. The stockpile needs constant replenishment.
I still think after the world goes all Road Warrior on us, the guys who control and let people rummage through the landfills will be the rich ones!