There's nothing in the federal legal tender law that I have read that prevents businesses and private citizens from conducting transactions with gold or silver or anything else they want.
What presently prohibits it is that many states (like my home state of Indiana) taxes the "sale" of gold and silver coins. If I have to pay 7% sales tax every time I want to trade my paper money for gold and silver money, it's never going to be feasilble for me.
If this state sales tax goes away, then we have a feasible alternative currency to the Federal Reserve Note. It would allow people to protect their earnings and savings from the inevitable rising inflation due to the Fed's huge expansion of the money supply.
Note: Indiana General Assembly just introduced senate bill #99 (Use and tax of gold and silver coins) that does just that. Sadly, it has little support among Indiana's legislators.
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