However, no government regulations require notification of purchases of precious metals themselves. The government doesn't want gold to be reported, but cash. Yes, it is generally necessary to report gold transactions to the IRS. However, tax obligations for the sale of precious metals such as gold and silver do not expire the moment they are sold.
Instead, sales of physical gold or silver must be reported on Schedule D of Form 1040 of your next tax return. You only pay taxes when you sell your gold for cash, not when you buy more gold with that money. These pieces include, among others, gold coins with fractional denominations; American Eagle gold or silver coins; any piece of foreign currency that has not been explicitly mentioned in the IRS's list of reportable items, as well as pieces of U.S. currency that were created after the list was created in the 1980s.
This includes coins and ingots weighing 1 kilogram or 1000 troy ounces respectively, along with any gold or silver item that has more than 50% of pure gold or silver containing silver. In other words, gold coins are taxed based on their total value, rather than just weighing the amount of gold they are made of.