Even gold and silver only have value because we believe they do, but they are just rocks... that's all.
Sorry, gold and silver have value in that they can be used for other things than a currency. That is the reason, when the lights go out and the computers are useless, gold and silver will still work as materials for creating things of use or for a means of value for trading goods.
I will admit that both are useful in terms of their efficiency in conducting electricity, but the amount we would need to fill this demand in society would leave tons left over if there was no other use for them. What gold and silver are mostly used for is decorative purposes(which is again only perceived value) and as a store of value(again, perceived value).
You can argue that everything has a practical value in one way or another, if not many others. Even paper money can be great for wiping your arse, but that doesn't mean that its value amounts to as much as we have attributed to it.
Silver is good for using a utensils for eating as well. Gold can be pounded and molded.
Gold also protects against solar rays.
They are very useful base elements.
Hands are sufficient for one to eat, especially if it is real food they are eating.
I really don't know why you are even arguing the most irrelevant part within my post. This seems like a waste of time because it's nothing to do with the issues that I was actually addressing in the post.