Price of gold would drop. Would disappear as currency. See “Rip Van Winkle Affair” Twilight zone original episode.
The commodity price of gold would collapse, but its intrinsic (giggle) value would make it ideal for use as US currency. I suggest a 50-50 split between gold and silver (or if not avaiable, gold and platinum metals) in a pretty swirl and as metallic foam to make larger coins that are lighter and have better stiffness, and make fakes easy to detect.