There have been periods in US history when we were on a gold and/or silver standard; then, it was illegal to hoard coinage metals, as this took money out of circulation and created inflation.
Instead, people with large supplies of gold and silver were obligated by law to deposit the specie with a federally chartered bank and receive in exchange an equivalent amount of a special class of paper money called "
gold certificates" and "
silver certificates." Often times the anti-hoarding laws were ignored, but there have been occasions (the Spanish-American War, both world wars, etc.) when they were enforced. Even then, there was usually no penalty beyond the exchange of specie for certificates.
Gold and silver fashioned into decorative and utilitarian objects -- candlesticks, eating utensils and the like -- was usually exempt from the hoarding laws. During times of extreme crisis, however, the government could obligate a person to turn over such things and get an equivalent value in certificates. The only time I know of when this was mandatory, however, was in the Confederacy during the Civil War.
Ore, almost by definition, belonged to the US government; mining operations that did not convert metal into coinage and certificates faced very severe penalties. That is why mints were built near big mining operations: US mint in Carson City built specifically to handle the Nevada silver rush, and the mint in San Francisco was built to deal with the California gold rush and latter the gold rush in Alaska. Anyone, be it a large mine owner making his daily deposit or a wildcat prospector on his monthy visit to town, could walk into an assay office with an amount of gold or silver and walk out with an equivalent amount of gold or silver coins or certificates.