At some point you'll come across an ad for bullion advising certain products are eligible for an IRA. What this means is you can have a self-directed IRA where you purchase certain gold coins and bars. As the saying goes, however, "The Devil is in the details."
While it's true you can purchase gold for an IRA to have for retirement, you legally cannot take possession of it until 59 1/2, unless you are willing to have the value of it treated as regular income that is taxable, plus incur an extra 10% penalty. In the meantime, you must have an approved custodian store the gold for you, where you won't have access to it. The main advantage of precious metals is that owning and storing them yourself eliminates any counterparty risk in owning it.
A common mantra passed amongst bullion stackers is "If you don't hold it, you don't own it." This is good advice for any tangible property, and especially so with precious metals. You're taking a risk that many years down the road the custodian holding your gold is still in business, still has it in their possession, and the ever-changing political landscape hasn't resulted in laws that make it harder or impossible to get your gold out.
While the idea of holding physical gold in an IRA is tempting, there are many variables outside of your control, which could put your bullion at risk. Realistically, you're better off taking that same amount of money you would've put towards gold in an IRA and buy it and store it yourself, or at least have a reputable security company store it, so you know it's in your possession and not subject to the whims of a third party.