In A Metal Mood (just a thought experiment)

 OK, the other day some people were  talking about how to go about using metals as a form of currency.  I got to thinking about how that would work.

Of course there is the possibility of small silver coins for this and that.  Actually moving the metal around physically.

But also I wondered if like minded people could have a sort Gold Club.  To get into the club you would enter your gold somehow into the group's holdings and then you could be issued documents, or bills that were redeemable for the metal represented.

The thing I wonder about also, is , would you spend them outside the group or not?

I know nothing about money or currency, but I have been thinking for a long time that we might need a kind of underground currency.  Just to get things done.  There used to be a lot of private currencies like in company towns or whatever.

Bitcoin and such are scary to me because they seem to rely on consensus only.