Silver from a medical perspective is valuable, maybe in small amounts but everyone will need some at least. And it works...trust me.
But gold and viler have been at the center of currency since the beginning of time. If I land in Pakistan with 100lb's of gold, I will be able to buy whatever I need...maybe the value has changed but it would still be seen as an asset worth trading for.
In America, there is a large movement to get your savings into gold and silver since the fiat currency can be devalued to nothing and all those people with millions in stocks will come out broke versus the guy who put away a couple bucks a week in gold or junk silver coins will still have savings to barter with.